al-Birjandi

Abd al-Ali Muhammad ibn Nizam ad-Din al-Birjandi (c. 854-934 AH / c. 1450-1528 CE) was a Persian astronomer, mathematician, and scholar from Birjand in Khurasan (modern eastern Iran). He was one of the most important scientific scholars of the late Timurid and early Safavid period and a major figure in the transmission of astronomical and mathematical knowledge in the Islamic tradition.

Al-Birjandi wrote extensive commentaries on the foundational astronomical texts of the Islamic tradition, including his commentary on Ulugh Beg's Zij (astronomical tables) — the Sharh Zij Ulugh Beg — and his commentary on Ali Qushji's Risalah fi al-Hay'ah, which deals with theoretical astronomy. He also wrote a commentary on Nasir ad-Din at-Tusi's Tadhkirah fil-Hay'ah, the most important medieval Islamic work on planetary theory.

In mathematics, he authored works on arithmetic (hisab) and geometry. His works contributed to the transmission and elaboration of Islamic mathematical and astronomical knowledge during a period of significant scientific activity in the Persianate world. He engaged with both the Ptolemaic astronomical tradition as transmitted and modified by Islamic scientists and the innovations introduced by scholars like at-Tusi.

Al-Birjandi is an important figure in the history of Islamic science, particularly the history of astronomy. His commentaries helped disseminate and clarify the complex astronomical models developed by the Maragha school. He passed away in approximately 934 AH. He is studied today primarily by historians of Islamic science interested in the transmission of astronomical thought from Maragha through the Timurid and early Safavid periods.