1251: Mongke Khan (蒙哥汗) became the khagan
Mongke (reign 1251–1259) was the fourth khagan of the Mongol Empire. His name meant eternal in the Mongolian language.
Due to disputes over succession, after his death, the Mongol Empire started to fracture. It was eventually divided into four khanates — the Golden Hordes, which at its peak occupied the land from Siberia to Eastern Europe, the Great Khanate in China which is the Yuan Dynasty, the Ilkhanate in the Middle East, and the Chagatai Khanate in Central Asia.
1252: Tax exempt for all clergies, Jews not mentioned
In 1489, Mirkhond (1433/1434–1489) wrote about the fourth emperor of the Mongol Empire, Mongke Khan (蒙哥汗, reign 1251–1259), issued a proclamation that exempted clergies of all religions from tax, but the Jews were not on the list. However, this point is subject to debate, for it was possible that the Jewish rabbis were not mentioned in the tax exemption list because of their insignificant population.
The Code of Yuan (元典章) in 1320 mentioned the need for everyone to pay tax, that is “Muslims, Nestorians, Jews (术忽, Shuhu), and Islamic Imams (答失蛮, Dashiman), except those in actual charge of temples and services, to pay taxes;” this implies that Jewish rabbis were part of the exception under the edict of 1252.