Ligdan Khan
In the early 17th century the Northern Yuan dynasty was divided into three parts: the Khalkha, Inner Mongols and Buryats. By the end of the 17th century, the power of the all-Mongolian Khan had greatly weakened and the decentralized Mongols had to face the rising new Jurchen statehood on the east. The last Mongol khagan was Ligdan Khan in the early 17th century. He got into conflicts with the Manchus over the looting of Chinese cities, and managed to alienate most Mongol tribes. In 1618, Ligden signed a treaty with the Ming dynasty to protect their northern border from the Manchus attack in exchange for thousands of taels of silver. Nurhaci Bagatur (Тэнгэрийн сүлдэт) who reunified the Jurchen tribes sent a letter to Ligdan Khan seeking alliance in fighting against the Ming dynasty. Ligdan denied the proposal mentioning that Nurhaci rules only three tumens of the Jurchens while Ligdan himself is a Genghisid ruling the 40 tumens of the Mongols, and that Nurhaci had better refrain from disturbing the Chinese cities-tributaries of him-of Ligdan Khan. In response, Nurhaci held it necessary to remind him that the 40 tumens are long gone and there are perhaps some six tumens of which only Chaharia recognizes Ligdan's power as Khan. Later Nurhaci managed to ally with the vassals of Ligdan Khan, the "taiji"s or princes of Southern Khalkha, Horchin, Horlos, etc., who pledged to support Nurhaci in his wars against the Ming dynasty. However their first allied actions were against their own suzerain Ligdan Khan, who they defeated in 1622.