History and Provenance of the " Chinese" Calendar in the Zīj-i Īlkhānī

This article sheds light upon a “Chinese” calendar described in the Zīj-i Īlkhānī. In previous studies, some characteristics of the calendar were ascribed to the “Uighurs” However, I will show that it was not originally associated with the Uighur. This “Chinese” calendar was brought to Iran by the Chinese Taoist Fu Mengchi who accompanied his ruler Hülegü. Fu Mengchi informed Nasīr al-DīnTūsī of the Chinese calendrical system, which Tūsī described in his Zīj-i Īlkhānī. Soon afterward, the calendar was included in the zīj of Muhyī al-DīnMaghribī, because it was only used among the Mongol ruling class and their Buddhist servants, who were called Uighur. Muhyī al-Dīn labeled the “Chinese” calendar the “Chinese-Uighur” calendar, and this title was repeated in subsequent zījes. Therefore, modern scholars have regarded the calendar as a product of the Uighurs. However, the title “Uighur” attached to the calendar in later zījes does not reflect the characteristics of the calendar, but rather the circumstances in which it was utilized.