Adai (Mongolian script: ; ), (1390–1438) was a khagan of the Northern Yuan dynasty, reigning from 1425 to 1438. After the prominent eastern Mongol chancellor Arughtai gave his allegiance to him, Adai briefly reunited most of the Mongol tribes under his banner. Early life The origin of Adai’s family lineage traced back to House of Ögedei or Khorchin (descended of Genghis Khan‘s brothers). Mongolian sources and Timurid era books recorded Adai was a son of Örüg Temür Khan and his family lineage traced back to Kadan, while Erdeniin Tobchi believe that he was related to Temüge or Hasar due to the interfamily marriages within the Borjigin clan. Adai’s family was a member of one of the eastern Mongol clans, Khorchin, which originated in the region of the Nen River to the east of the Greater Khingan Range. Even before his proclamation as the Khagan, Adai almost succeeded in unifying western Mongol territory by defeating the Oirats. Alarmed by the possible resurgence of another Genghis Khan, the Ming dynasty provided support to the Oirats and their allies among the western Mongol clans, successfully turning the tide by first recovering and then launching counteroffensives against the eastern and central Mongol clans. Arughtai Chingsang installed Adai on the throne as Khagan of the Northern Yuan after discussing the matter with the family of Khasar. Reign During his rule, Adai was able to consolidate and expand his power, eventually unifying both the central and eastern Mongol territories in 1425. However, his conquest of western Mongol territory was checked by the Oirats and both sides continued the war for unification for decades. Riding on the success of unifying central and eastern Mongol territories, Adai proclaimed himself as Khagan with support of central and eastern Mongol clans in 1425, the same year his rival khan in the west, Oyiradai, was killed. Adai and Arughtai crushed the Oirats and killed several of their leaders. After capturing the Oirat nobles, Adai married Ugetchi Khashikha's wife, Öljeitü the Beauty, who had been a consort of Elbeg Khan (r.1392–1399), and enslaved Bahamu's son (the future Toghan taishi). Although Adai Khan’s authority did not fully reach western Mongols who did not recognize him as supreme ruler, the western Mongol clans did not have a khan of their own so Adai Khan remained as the sole Mongol ruler for the next eight years, at least in name. Elbeg's daughter and the Oirat