Around 786, the fifth Caliph of the Abbasid dynasty began with Caliph Harun al-Rashid, a leader who encouraged learning, including the translation of many major Greek treatises into Arabic, such as Euclid’s *Elements.* Al-Ma’mun (786–833), the next Caliph, was even more interested in scholarship, creating the House of Wisdom in Baghdad, one of several scientific centers in the Islamic Empire. Here, too, Greek works such as Galen’s medical writings and Ptolemy’s astronomical treatises were translated, not by language experts ignorant of mathematics, but by scientists and mathematicians such as Al-Kindi (801–873), Muhammad ibn Musa al-Khuwarizmi (see below), and the famous translator Hunayn ibn Ishaq (809–873).

A famous Caliph whose reign was immortalized in the book *One Thousand and One Arabian Knights,* Harun al-Rashid promoted education among his subjects, including the mathematical writings of the Greeks.