Adai (1390–1438) was the Mongol Khan of the Northern Yuan dynasty based in Mongolia. After the prominent eastern Mongolian chancellor, Arughtai, threw his allegiance to him, he briefly reunited most of the Mongols under his banner.
Lineage and early life
The origin of Adai’s family lineage traced back to Kadan and Hasar due to the interfamily marriages within the Borjigin clan. Mongolian sources also say Adai was a son of Örüg Temür Khan.<ref>東京外国語大学. アジア・アフリカ言語文化研究所-アジア・アフリカ言語文化研究, Issues 27-30, p.152</ref><ref>Mongolian rulers</ref> Adai’s family was a member of eastern Mongol clans, Khorchin, originated in the region of Nen River to the east of 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’s era, 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 eastern and central Mongol clans.
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 sided 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 rivalry khan in the west, Oyiradai was killed. Adai and Arughtai crushed the Oirats and killed several leaders of them. After capturing the Oirat nobles, Adai, married Gulichi's wife, Öljeitü the Beauty, who had been a consort of Elbeg Khan (r.1392–1399) and enslaved Bahamu's son (future Toghan taishi). Although Adai Khan’s authority did not fully reach western Mongols who did not recognize him as supreme ruler, 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 taishi Bahamu's widow, Samar, persuaded the Khan to release her son now named Toghan to western Mongolia. However, in 1433, Toghan raised a rebellion and western Mongols finally crowned Toghtoa Bukha (or Toγtoγa Buqa) with the title of Tayisung Khan as their next new khan, which resulted in half a decade of the simultaneous existence of two khans supported by opposing Mongol clans.
After two decisive campaigns in 1422 and 1423, Adai Khan lost all of the territory gained in the past and in 1430, the third Oirat victory wiped out his major strength, after which he could no longer mount any effective offensives and was forced on the defensive. Both sides attempted to utilize the stalemate to prepare for the next stage but Adai Khan could not recover from the previous loss. The Oirats soon launched another round of offensives and in the fourth decisive Oirat victory in 1434 in which Adai Khan’s major advisors, Arughtai and others, were killed, Adai Khan’s downfall was certain.
In 1438, Adai Khan was defeated in Ejene when his territory was overran by the Oirats and their allies. Adai sought refuge in the Eight White Tents of Genghis Khan, however, being unarmed, he was murdered by Togoon taishi of the Oirat.<ref>Johan Elverskog-Our great Qing: the Mongols, Buddhism and the state in late imperial China, p.53</ref>