‘Abd ar-Rahman III
‘Abd ar-Rahman III ('Abd al-Rahman ibn Muhammad ibn 'Abd Allah) (January 11, 889 - October 15, 961). The eighth (and arguably the greatest) Umayyad emir of Spain. He ruled from 912 to 961. He ascended to the throne when he was twenty-two years of age and reigned for half a century as the most powerful prince of the Umayyad dynasty in Iberia.
Called al-Nasir, or the Defender (of the Faith), he was born at Cordoba, and was the son of Prince Muhammad. Succeeding to an emirate diminished by provincial governors who acted like independent rulers, ‘Abd ar-Rahman at once set out to assert Umayyad authority over all his territories. Initially, he had to suppress the dangerous revolt led by 'Umar ibn Hafsun. In 913, he attacked Seville, a city that had allied with Hafsun, conquering it on December 20. The following year, he campaigned in the Rayya mountains near Malaga, where his mild treatment gained him the surrender of most of the Christian castles. In 917, Hafsun died, but the struggle was continued by his son, who surrendered only after the fall of Malaga on January 21, 928.
Seville and Cremona submitted in 917, Bobastro was captured in 928 and Toledo, the last of the wayward cities, surrendered in 932. The emir checked the advance of the Christian prince Ordono II of Leon (d. 951) in 920.
Once having al-Andalus firmly under his rule, 'Abd ar-Rahman restarted his war against King Ordono II of Leon, who had taken advantage of the previous troublesome situation to capture some bondary areas and to menace the Umayyad territory. In 920, the emir's troops gained a first victory at Junquera (Valdejunquera). This was one of several defeats ‘Abd ar-Rahman inflicted on the Christian kingdoms of Leon and Navarre, checking their expansion.
In 924, Abd 'ar Rahman sacked the Basque capital of Pamplona of King Sancho I. An attempt by Ramiro, the son of Ordono II, to help Toledo was repulsed in 932.
During this time, ‘Abd ar-Rahman built up a navy unmatched anywhere in the world. With this navy, ‘Abd ar-Rahman proceeded to seize part of Morocco from the Fatimids. In 923, Ceuta was captured and the whole of the central Maghrib subdued, with the exception of the region of Tahert. This period also saw the formation of parties which were in the end to cause the greatest disorder: the Slav party and the Berber party. The Slavs were prisoners from eastern Europe, Italy and northern Spain and soon formed a large class in Cordoban society. The Berber party was to play a part in the early tenth century (of the Christian calendar).
By 929, ‘Abd ar-Rahman felt confident enough to assume the title of amir al-mu'minin (“Commander of the Believers”). On January 16, 929, he declared himself as the Caliph of Cordoba, effectively breaking all ties with the Fatimid and 'Abbasid caliphs, thereby restoring in Spain the Umayyad caliphate of Cordoba. His ancestors in Iberia had been content with the title of emir. The caliphate was thought only to belong to the prince who ruled over the sacred cities of Mecca and Medina. However, the force of this tradition had been so weakened that 'Abd ar-Rahman could proclaim himself caliph, and the assumption of the title gave him increased prestige with his subjects, both in Iberia and Africa. 'Abd ar-Rahman based his claim to the caliphate on his Ummayyad ancestry. The Umayyads had held undisputed control of the caliphate until they were overthrown by the 'Abbasids.
In 930, Ibn Marwan surrendered, and in 932, Toledo was captured. At this point all Arabs, Iberians and Berbers submitted to 'Abd ar-Rahman. In 931, in order to counter the increasing Fatimid power in North Africa, the caliph had helped Berbers to conquer Ceuta and other territories, which accepted his suzerainty. This was, however, lost a few years later.
In 934, after reassuring his supremacy over Pamplona and Alava, 'Abd ar-Rahman forced Ramiro, the son of Ordono of Leon, to retreat up to Burgos. In 937, he conquered some thirthy castles in Leon and then compelled again the Navarese queen, Toda, to submit to him as a vassal. Then came the time for Muhammad ibn Hashim at-Tugib, governor of Zaragoza, who had allied with Ramiro but was pardoned after the captured of his city.
Despite their early defeats, Ramiro II and Toda were able to crush the caliphate army in 939 at the Battle of Simancas, most likely due to treason from Arabic elements in the caliph's army. After this defeat, 'Abd ar-Rahman stopped taking part in person in the military campaigns. His cause was however helped by Fernan Gonzalez of Castile, one of the Christian leaders at Simancas, who declared war against Ramiro, only to be defeated after a while. Ramiro's victory at Simancas enabled the advance of the Leonine border from the Duero to the Tormes.
In 951, he signed a peace with the new king of Leon, Ordono III, in order to have free hand against the Fatimids in North Africa. He was, however, able only to launch an expedition against Ifriqiya, in the area of Tunis.
In 954, the Fatimids made a raid on the Spanish shore near Almeria. As a reprisal, ‘Abd ar-Rahman burned Marsa‘l-Kharaz on the North African coast. About 955, ‘Abd ar-Rahman’s help was invoked by King Sancho and Queen Tota of Navarre against Ordono IV, an event without precedent in the annals of Muslim Spain. Ordono III's son and successor, Sancho I, had been deposed by his cousin Ordono IV. Sancho, together with Toda of Navarre, sued for an alliance with Cordoba. In exchange for some castles, 'Abd ar-Rahman helped them to take back Zamora in 959 and Oviedo in 960 and to overthrow Ordono IV.
'Abd ar-Rahman spent the rest of his years in his new palace outside Cordoba. He died in October 961 and was succeeded by his son al-Hakam II.
‘Abd ar-Rahman constructed near Cordoba the town of Madinat al-Zahra’ (Medina Azahara) for his own residence. Ultimately, ‘Abd ar-Rahman’s greatest legacy was the transformation of Cordoba into the greatest cultural center in the Western world, a distinction Cordoba would hold for over two centuries. 'Abd ar-Rahman expanded the city's library, which would help make Cordoba the intellectual center of Western Europe.
By the end of ‘Abd ar-Rahman’s reign, the splendor of Cordoba rivaled that of Baghdad and Constantinople, the great cultural centers of the East. Under 'Abd ar-Rahman, Islamic Cordoba became a city of beauty and enlightenment.
Rahman, 'Abd ar- see ‘Abd ar-Rahman III
'Abd al-Rahman ibn Muhammad ibn 'Abd Allah see ‘Abd ar-Rahman III
Nasir, al- see ‘Abd ar-Rahman III
Defender of the Faith see ‘Abd ar-Rahman III
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Abu al-Fida
Abu al-Fida (Abulfida) (Abul Fida Ismail Hamvi) (Abu al-Fida' Isma'il ibn Mahmud al-Malik al-Mu'ayyad 'Imad Ad-din) (Abulfeda) (Abu Alfida) (November, 1273 - October 27, 1331). Arab historian and geographer.
Abu al-Fida was born in Damascus, where his father Malik ul-Afdal, brother of the prince of Hamah, had fled from the Mongols. He was a descendant of Ayyub, the father of Saladin. In his boyhood, Abu al-Fida devoted himself to the study of the Qur'an and the sciences, but from his twelfth year was almost constantly engaged in military expeditions, chiefly against the crusaders.
In 1285, Abu al-Fida was present at the assault of a stronghold of the Knights of St. John, and took part in the sieges of Tripoli (1289), Acre (1291) and Qal'at ar-Rum. Tripoli and Acre were the last strongholds of the Crusaders.
In 1298, Abu al-Fida entered the service of the Mameluke Sultan Malik al-Nasir and after twelve years was invested by him with the governorship of Hamah. In 1310, Abu al-Fida was appointed governor of the city of Hamah, over which he ruled with almost absolute power. In 1312, Abu al-Fida was made a prince with the title Malik us-Salhn, and in 1320, he was given the title of sultan with the title Malik ul-Mu'ayyad and the right to transmit the title to his descendants.
Abu al-Fida’s most important work was An Abridgment of the History of the Human Race, a text that traces human history from the creation of the world until 1329. This work is especially valuable as a source for the period of the Crusades. He also wrote Geography, which is valued primarily for its description of the Muslim world. Geography was founded on the works of his predecessors, including the works of Ptolemy and Muhammad al-Idrisi. A long introduction on various geographical matters is followed by twenty-eight sections dealing in tabular form with the chief towns of the world. After each name are given the longitude, latitude, climate, spelling, and then observations generally taken from earlier authors.
Abulfeda crater, a crater on the Moon, is named for Abu al-Fida.
Fida, Abu al- see Abu al-Fida
Abulfida see Abu al-Fida
Abul Fida Ismail Hamvi see Abu al-Fida
Abu al-Fida' Isma'il ibn Mahmud al-Malik al-Mu'ayyad 'Imad Ad-din see Abu al-Fida
Abulfeda see Abu al-Fida
Abu Alfida see Abu al-Fida
*****‘Abd ar-Rahman III ('Abd al-Rahman ibn Muhammad ibn 'Abd Allah) (January 11, 889 - October 15, 961). The eighth (and arguably the greatest) Umayyad emir of Spain. He ruled from 912 to 961. He ascended to the throne when he was twenty-two years of age and reigned for half a century as the most powerful prince of the Umayyad dynasty in Iberia.
Called al-Nasir, or the Defender (of the Faith), he was born at Cordoba, and was the son of Prince Muhammad. Succeeding to an emirate diminished by provincial governors who acted like independent rulers, ‘Abd ar-Rahman at once set out to assert Umayyad authority over all his territories. Initially, he had to suppress the dangerous revolt led by 'Umar ibn Hafsun. In 913, he attacked Seville, a city that had allied with Hafsun, conquering it on December 20. The following year, he campaigned in the Rayya mountains near Malaga, where his mild treatment gained him the surrender of most of the Christian castles. In 917, Hafsun died, but the struggle was continued by his son, who surrendered only after the fall of Malaga on January 21, 928.
Seville and Cremona submitted in 917, Bobastro was captured in 928 and Toledo, the last of the wayward cities, surrendered in 932. The emir checked the advance of the Christian prince Ordono II of Leon (d. 951) in 920.
Once having al-Andalus firmly under his rule, 'Abd ar-Rahman restarted his war against King Ordono II of Leon, who had taken advantage of the previous troublesome situation to capture some bondary areas and to menace the Umayyad territory. In 920, the emir's troops gained a first victory at Junquera (Valdejunquera). This was one of several defeats ‘Abd ar-Rahman inflicted on the Christian kingdoms of Leon and Navarre, checking their expansion.
In 924, Abd 'ar Rahman sacked the Basque capital of Pamplona of King Sancho I. An attempt by Ramiro, the son of Ordono II, to help Toledo was repulsed in 932.
During this time, ‘Abd ar-Rahman built up a navy unmatched anywhere in the world. With this navy, ‘Abd ar-Rahman proceeded to seize part of Morocco from the Fatimids. In 923, Ceuta was captured and the whole of the central Maghrib subdued, with the exception of the region of Tahert. This period also saw the formation of parties which were in the end to cause the greatest disorder: the Slav party and the Berber party. The Slavs were prisoners from eastern Europe, Italy and northern Spain and soon formed a large class in Cordoban society. The Berber party was to play a part in the early tenth century (of the Christian calendar).
By 929, ‘Abd ar-Rahman felt confident enough to assume the title of amir al-mu'minin (“Commander of the Believers”). On January 16, 929, he declared himself as the Caliph of Cordoba, effectively breaking all ties with the Fatimid and 'Abbasid caliphs, thereby restoring in Spain the Umayyad caliphate of Cordoba. His ancestors in Iberia had been content with the title of emir. The caliphate was thought only to belong to the prince who ruled over the sacred cities of Mecca and Medina. However, the force of this tradition had been so weakened that 'Abd ar-Rahman could proclaim himself caliph, and the assumption of the title gave him increased prestige with his subjects, both in Iberia and Africa. 'Abd ar-Rahman based his claim to the caliphate on his Ummayyad ancestry. The Umayyads had held undisputed control of the caliphate until they were overthrown by the 'Abbasids.
In 930, Ibn Marwan surrendered, and in 932, Toledo was captured. At this point all Arabs, Iberians and Berbers submitted to 'Abd ar-Rahman. In 931, in order to counter the increasing Fatimid power in North Africa, the caliph had helped Berbers to conquer Ceuta and other territories, which accepted his suzerainty. This was, however, lost a few years later.
In 934, after reassuring his supremacy over Pamplona and Alava, 'Abd ar-Rahman forced Ramiro, the son of Ordono of Leon, to retreat up to Burgos. In 937, he conquered some thirthy castles in Leon and then compelled again the Navarese queen, Toda, to submit to him as a vassal. Then came the time for Muhammad ibn Hashim at-Tugib, governor of Zaragoza, who had allied with Ramiro but was pardoned after the captured of his city.
Despite their early defeats, Ramiro II and Toda were able to crush the caliphate army in 939 at the Battle of Simancas, most likely due to treason from Arabic elements in the caliph's army. After this defeat, 'Abd ar-Rahman stopped taking part in person in the military campaigns. His cause was however helped by Fernan Gonzalez of Castile, one of the Christian leaders at Simancas, who declared war against Ramiro, only to be defeated after a while. Ramiro's victory at Simancas enabled the advance of the Leonine border from the Duero to the Tormes.
In 951, he signed a peace with the new king of Leon, Ordono III, in order to have free hand against the Fatimids in North Africa. He was, however, able only to launch an expedition against Ifriqiya, in the area of Tunis.
In 954, the Fatimids made a raid on the Spanish shore near Almeria. As a reprisal, ‘Abd ar-Rahman burned Marsa‘l-Kharaz on the North African coast. About 955, ‘Abd ar-Rahman’s help was invoked by King Sancho and Queen Tota of Navarre against Ordono IV, an event without precedent in the annals of Muslim Spain. Ordono III's son and successor, Sancho I, had been deposed by his cousin Ordono IV. Sancho, together with Toda of Navarre, sued for an alliance with Cordoba. In exchange for some castles, 'Abd ar-Rahman helped them to take back Zamora in 959 and Oviedo in 960 and to overthrow Ordono IV.
'Abd ar-Rahman spent the rest of his years in his new palace outside Cordoba. He died in October 961 and was succeeded by his son al-Hakam II.
‘Abd ar-Rahman constructed near Cordoba the town of Madinat al-Zahra’ (Medina Azahara) for his own residence. Ultimately, ‘Abd ar-Rahman’s greatest legacy was the transformation of Cordoba into the greatest cultural center in the Western world, a distinction Cordoba would hold for over two centuries. 'Abd ar-Rahman expanded the city's library, which would help make Cordoba the intellectual center of Western Europe.
By the end of ‘Abd ar-Rahman’s reign, the splendor of Cordoba rivaled that of Baghdad and Constantinople, the great cultural centers of the East. Under 'Abd ar-Rahman, Islamic Cordoba became a city of beauty and enlightenment.
Rahman, 'Abd ar- see ‘Abd ar-Rahman III
'Abd al-Rahman ibn Muhammad ibn 'Abd Allah see ‘Abd ar-Rahman III
Nasir, al- see ‘Abd ar-Rahman III
Defender of the Faith see ‘Abd ar-Rahman III
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Abu Abdullah al-Bakri
Abu Abdullah al-Bakri (Abu ‘Ubaydallah al-Bakri) (d. 1094). Arab geographer.He never left Cordova, but in 1067-68, he compiled information concerning the Western Sudanic region, based on both oral accounts of traders and previous written works. Of the latter the most important was that of Muhammad ibn Yusuf al-Warraq (904-973) which is now lost.Al-Bakri’s description of Ghana, written shortly after its fall, is one of the best sources of information for that empire.
Abu ‘Ubaydallah al-Bakri see Bakri
Abu Abdullah al-Bakri
Abu Abdullah al-Bakri (Abu ‘Ubaydallah al-Bakri) (d. 1094). Arab geographer.He never left Cordova, but in 1067-68, he compiled information concerning the Western Sudanic region, based on both oral accounts of traders and previous written works. Of the latter the most important was that of Muhammad ibn Yusuf al-Warraq (904-973) which is now lost.Al-Bakri’s description of Ghana, written shortly after its fall, is one of the best sources of information for that empire.
Abu ‘Ubaydallah al-Bakri see Bakri
Abu Abdullah al-Bakri
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Abu al-Fida
Abu al-Fida (Abulfida) (Abul Fida Ismail Hamvi) (Abu al-Fida' Isma'il ibn Mahmud al-Malik al-Mu'ayyad 'Imad Ad-din) (Abulfeda) (Abu Alfida) (November, 1273 - October 27, 1331). Arab historian and geographer.
Abu al-Fida was born in Damascus, where his father Malik ul-Afdal, brother of the prince of Hamah, had fled from the Mongols. He was a descendant of Ayyub, the father of Saladin. In his boyhood, Abu al-Fida devoted himself to the study of the Qur'an and the sciences, but from his twelfth year was almost constantly engaged in military expeditions, chiefly against the crusaders.
In 1285, Abu al-Fida was present at the assault of a stronghold of the Knights of St. John, and took part in the sieges of Tripoli (1289), Acre (1291) and Qal'at ar-Rum. Tripoli and Acre were the last strongholds of the Crusaders.
In 1298, Abu al-Fida entered the service of the Mameluke Sultan Malik al-Nasir and after twelve years was invested by him with the governorship of Hamah. In 1310, Abu al-Fida was appointed governor of the city of Hamah, over which he ruled with almost absolute power. In 1312, Abu al-Fida was made a prince with the title Malik us-Salhn, and in 1320, he was given the title of sultan with the title Malik ul-Mu'ayyad and the right to transmit the title to his descendants.
Abu al-Fida’s most important work was An Abridgment of the History of the Human Race, a text that traces human history from the creation of the world until 1329. This work is especially valuable as a source for the period of the Crusades. He also wrote Geography, which is valued primarily for its description of the Muslim world. Geography was founded on the works of his predecessors, including the works of Ptolemy and Muhammad al-Idrisi. A long introduction on various geographical matters is followed by twenty-eight sections dealing in tabular form with the chief towns of the world. After each name are given the longitude, latitude, climate, spelling, and then observations generally taken from earlier authors.
Abulfeda crater, a crater on the Moon, is named for Abu al-Fida.
Fida, Abu al- see Abu al-Fida
Abulfida see Abu al-Fida
Abul Fida Ismail Hamvi see Abu al-Fida
Abu al-Fida' Isma'il ibn Mahmud al-Malik al-Mu'ayyad 'Imad Ad-din see Abu al-Fida
Abulfeda see Abu al-Fida
Abu Alfida see Abu al-Fida
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Abu al-Wafa (Abul Wefa)
Abul Wefa (Abul Wafa' Buzjani) (Abu al-Wafa' Muhammad ibn Muhammad ibn Yahya ibn Isma'il ibn al-'Abbas al-Buzjani) (June 10, 940 - July 1, 998). Mathematician and astronomer who played a major role in the development of sines and cosines as they apply to the field of trignonometry. These he used to correct astronomical calculations carried forward from classical into Islamic times. Born on June 10, 940, in either Buzshan, Khorasan Province, or Buzadhan, Kuhistan Province, Iran, during the reign of the ‘Abbasid caliph al-Mutaqqi, Abul Wefa lived during a period of extraordinary cultural and intellectual productivity. His own fields of accomplishment, mathematics and astronomy, were already widely recognized as essential elements of high Islamic civilization. Very little is known about Abul Wefa’s early life. Apparently, his early education in mathematics occurred under the tutelage of two uncles, one of whom (Abu Amr al-Mughazili) had received formal training from the famous geometricians Abu Yahya al-Marwazi and Abu ’l Ala ibn Karnib. Whatever the possible source of patronage for the young man’s further education may have been, his decision to move to Baghdad at the age of nineteen (in 959) greatly benefitted the ‘Abbasid court. Baghdad at this time was politically troubled, following the seizure of de facto control by a military clique headed by the Persian Buyid emirs. Thereafter, the Buyids dominated the house of the caliphs until their fall from power in 1055. The Buyids were inclined to favor talented Persians who were drawn toward scholarly circles in the center of the empire. It is reported, for example, that it was Abul Wefa, himself then forty years of age and well established (circa 980), who introduced the Persian scholar and philosopher Abu Hayyan al-Tawhidi into the Baghdad entourage of the vizier Ibn Sa’dan. Abu Hayyan soon became famous under the vizier’s patronage, composing a major work, al-Imta’ wa’l mu’anasa (a collection of notes drawn from philosophical and literary “salon” meetings), with a dedication to Ibn Sa’dan. Patronage for Abul Wefa’s work in courtly circles, however, must have come from a different milieu, that of the so-called Baghdad School. This scientific assembly flourished in the‘Abbasid capital in the last century before its conquest by the Seljuk Turks in 1055. According to some historians, patronage for the natural sciences in particular came precisely during the period in which Abul Wefa passed into the main stages of his scholarly career. The Buyid emir Adud al-Dawlah (978-983) had nurtured an interest in astronomy through his own studies. He passed this interest on to his son, Saraf al-Dawlah, who built an observatory next to his palace and called scholars from all regions of the empire to glorify the reputation of his reign by carrying out scientific experiments. Abul Wefa was among this group. The environment for learning in the Baghdad School, with its circle of eminent Islamic scientists, may explain how the young Persian scholar mastered so many technical fields in such a limited period of time. Beyond mere speculation regarding Abul Wefa’s early personal contacts, however, one must consider the importance of translation work in the Baghdad School. Abul Wefa himself translated the work of the Greek algebraist Diophantus (fl. c. 250), who had explored the field of indeterminate algebraic equations. Abul Wefa was also known for his studies of, and commentaries on, Euclid. There are, however, no surviving texts to indicate what use he made of the work of these two forerunners of the classical pre-Islamic period. By contrast, Abul Wefa’s attention to the work of the second century Greek astronomer Ptolemy not only contributed to the preservation and transmission to the medieval West of the classical knowledge contained in Ptolemy’s Mathematike suntaxis (c. 150; Almagest) but also earned for him an original and lasting reputation as an Islamic mathematician. The Almagest examined the field of trigonometry, which proposed mathematical relationships in terms of the angles and sides of right triangles. This called for the development of sines, or systematic relationships defined in a right triangle working from one of the acute angles, symbolically represented as A. Modern trigonometry expresses this relationship as sin A = a/c, or sin A is equal to the ratio of the length of the side opposite that angle (a) to the length of the hypotenuse (c). Ptolemy, in pioneering the field of spherical trigonometry, had laid down an approximate method for calculating sines (which he described as “chords”). Abul Wefa, however, drew on his studies of Indian precedents in the field of trigonometry that were unknown to Ptolemy, as well as models provided by Abul Wefa’s predecessor al-Battani (858-929), to perfect Ptolemy’s chords. This was done by applying algebraic, instead of geometric, methods of systematizing the sines. In particular, Abul Wefa’s development of the “half-chord” made it possible to achieve much more precise measurements that would eventually be used in surveying and navigation. The most immediate application of his tables of sines, however, was in the field of astronomy. One of Abul Wefa’s contributions which left a legacy that lasted for many centuries involved the study of evection, or irregularity, in the longitude of the moon. Later European commentators looked at the Islamic astronomer’s work and concluded that he, not Tycho Brahe (1546-1601), had been the first scientist to posit the theory of the “third inequality of the moon.” Although this theory was later proved to be erroneous, the debate at least drew attention to the importance of Abul Wefa’s originality in the field. Abul Wefa himself compiled, in addition to his well-known tables of sines, a book of astronomical tables entitled Zif al-wadith (that which is clear). Like his earlier work on sines, this text is not extant in the original. Scholars tend to agree, however, that certain anonymous manuscripts preserved in European libraries, such as the Zij al-shamil, are taken from Abul Wefa’s work. Works that have survived and that have been at least partially translated include a book of arithmetic entitled Kitab fi ma yahtaj ilayh al-kuttab wa l-‘ummal min ‘ilm al-hisab (Book on What is Necessary from the Science -- of Arithmetic for Scribes and Businessmen [961-976]), the Kitab fi ma yahtaj ilayh al-sani ‘min al-a’mal al-handasiyha (Book on What is Necessary from Geometric Construction for the Artisan [after 990]), and a book entitled Kitab al-kamil. It is thought that Abul Wefa may have still been living in Baghdad at the time of his death in 998 (July 1, 998). The crater Abul Wafa on the Moon is named after Abul Wefa. Wefa, Abul see Abul Wefa Abul Wafa' Buzjani see Abul Wefa Buzjani, Abul Wafa' see Abul Wefa Abu al-Wafa' Muhammad ibn Muhammad ibn Yahya ibn Isma'il ibn al-'Abbas al-Buzjani see Abul Wefa | |
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He is also credited with compiling the tables of sines and tangents at 15' intervals. He also introduced the sec and cosec functions, as well studied the interrelations between the six trigonometric lines associated with an arc. His Almagest was widely read by medieval Arabic astronomers in the centuries after his death. He is known to have written several other books that have not survived.
He was born in Buzhgan, (now Torbat-e Jam) in Khorasan (in today's Iran). At age 19, in 959 AD, he moved to Baghdad and remained there for the next forty years, and died there in 998. He was a contemporary of the distinguished scientists Al-Quhi and Al-Sijzi who were in Baghdad at the time and others like Abu Nasr ibn Iraq, Abu-Mahmud Khojandi, Kushyar ibn Labban and Al-Biruni. In Baghdad, he received patronage by members of the Buyid court.
Abu Al-Wafa' was the first to build a wall quadrant to observe the sky. It has been suggested that he was influenced by the works of Al-Battani as the latter describes a quadrant instrument in his Kitāb az-Zīj. His use of tangent helped to solve problems involving right-angled spherical triangles, and developed a new technique to calculate sine tables, allowing him to construct more accurate tables than his predecessors.In 997, he participated in an experiment to determine the difference in local time between his location and that of al-Biruni (who was living in Kath, now a part of Uzbekistan). The result was very close to present-day calculations, showing a difference of approximately 1 hour between the two longitudes. Abu al-Wafa is also known to have worked with al-Kuhi, who was a famous maker of astronomical instruments. While what is extant from his works lacks theoretical innovation, his observational data were used by many later astronomers, including al-Biruni's.
Among his works on astronomy, only the first seven treatises of his Almagest (Kitāb al-Majisṭī) are now extant. The work covers numerous topics in the fields of plane and spherical trigonometry, planetary theory, and solutions to determine the direction of Qibla.
He established several trigonometric identities such as sin(a ± b) in their modern form, where the Ancient Greek mathematicians had expressed the equivalent identities in terms of chords.
He also discovered the law of sines for spherical triangles:
Some sources suggest that he introduced the tangent function, although other sources give the credit for this innovation to al-Marwazi.
- Almagest (Kitāb al-Majisṭī).
- A book of zij called Zīj al‐wāḍiḥ, no longer extant.
- "A Book on Those Geometric Constructions Which Are Necessary for a Craftsman", (Kitāb fī mā yaḥtaj ilayh al-ṣāniʿ min al-aʿmāl al-handasiyya).
- "A Book on What Is Necessary from the Science of Arithmetic for Scribes and Businessmen", (Kitāb fī mā yaḥtaj ilayh al-kuttāb wa’l-ʿummāl min ʾilm al-ḥisāb). This is the first book where negative numbers have been used in the medieval Islamic texts.
The crater Abul Wáfa on the Moon is named after him.
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