Genghis Khan's third son was chosen as heir to stop his brothers fighting
Genghis Khan had older sons, but Jochi and Chagatai could not stop quarrelling, so the succession passed to the third, Ögedei. He turned out to be more than a compromise. Under him Mongol armies finished off northern China, took Persia and rode into Europe, while he built a capital and a working bureaucracy.
Ögedei grew up amid his father Temüjin's violent climb to power. At 17 he was badly wounded in a defeat by Jamukha's army and left on the field until Borokhula, an adopted brother of his father, carried him off. When Temüjin became Genghis Khan in 1206, Ögedei received an appanage of several clans along the Emil and Hobok rivers, with the Jalayir commander Ilugei as his tutor. He first campaigned on his own against the Jin dynasty in 1211.
His reputation was made in Central Asia. At Urganch, where Jochi and Chagatai were feuding over tactics, Genghis handed Ögedei overall command, and the city fell in 1221. The brothers' earlier brawl over the succession, prompted by the Empress Yisui's demand that an heir be named, had already ended in agreement on Ögedei. After Genghis died in 1227 their younger brother Tolui acted as regent, and in 1229 a kurultai on the Kherlen River proclaimed Ögedei khan once he had ritually refused three times.
Expansion resumed quickly. Chormaqan Noyan led a force of 30,000 to 50,000 into Persia in 1230 and gradually absorbed the whole region, isolating the Khwarazmian prince Jalal al-Din. Invasions of Korea began in 1231, and the Jin state collapsed with the fall of Caizhou in 1234, helped late in the day by the Song, who soon turned on the Mongols themselves. By 1241 his nephew Batu and the general Subutai had beaten Polish forces at Legnica and Hungarians at Mohi before pulling back, most likely to settle the succession after Ögedei died that December.
At home he worked with officials such as Yelü Chucai on tax collection, ortogh trading partnerships and regional administrations, and in the 1230s he founded Karakorum. History has long ranked him below his father and dwelt on his heavy drinking, yet contemporaries found him charming, good-natured and sharp. His son Güyük succeeded him.
Source: Ögedei Khan