fl. 800s

Banu Musa was the name of three brothers, Jafar, Ahmad, and Al-Hasan, all important ninth-century Arab mathematicians who continued and expanded the mathematics developed by the early Greeks. The three brothers received an excellent education in Baghdad, where they studied geometry, mathematics, and astronomy. Their scientific contributions included the concept of geometric proofs, as well as their accurate measurement of the length of a year (365 days and 6 hours long).