section_path: History/Death of Genghis Khan and expansion under Ögedei (1227–1241)
section_name: Death of Genghis Khan and expansion under Ögedei (1227–1241)
paragraph_text: Death of Genghis Khan and expansion under Ögedei (1227–1241)
  
  Genghis Khan died on 18 August 1227, by which time the Mongol Empire ruled from the Pacific Ocean to the Caspian Sea, an empire twice the size of the Roman Empire or the Muslim Caliphate at their height. Genghis named his third son, the charismatic Ögedei, as his heir. According to Mongol tradition, Genghis Khan was buried in a secret location. The regency was originally held by Ögedei's younger brother Tolui until Ögedei's formal election at the kurultai in 1229.
  
  Among his first actions Ögedei sent troops to subjugate the Bashkirs, Bulgars, and other nations in the Kipchak-controlled steppes. In the east, Ögedei's armies re-established Mongol authority in Manchuria, crushing the Eastern Xia regime and the Water Tatars. In 1230, the great Khan personally led his army in the campaign against the Jin dynasty of China. Ögedei's general Subutai captured the capital of Emperor Wanyan Shouxu in the siege of Kaifeng in 1232. The Jin dynasty collapsed in 1234 when the Mongols captured Caizhou, the town to which Wanyan Shouxu had fled. In 1234, three armies commanded by Ögedei's sons Kochu and Koten and the Tangut general Chagan invaded southern China. With the assistance of the Song dynasty the Mongols finished off the Jin in 1234.
  
  Many Han Chinese and Khitan defected to the Mongols to fight against the Jin. Two Han Chinese leaders, Shi Tianze, Liu Heima (劉黑馬, Liu Ni), and the Khitan Xiao Zhala defected and commanded the 3 Tumens in the Mongol army. Liu Heima and Shi Tianze served Ogödei Khan. Liu Heima and Shi Tianxiang led armies against Western Xia for the Mongols. There were four Han Tumens and three Khitan Tumens, with each Tumen consisting of 10,000 troops. The Yuan dynasty created a Han army 漢軍 from Jin defectors, and another of ex-Song troops called the Newly Submitted Army 新附軍.
  
  In the West Ögedei's general Chormaqan destroyed Jalal ad-Din Mingburnu, the last shah of the Khwarizmian Empire. The small kingdoms in southern Persia voluntarily accepted Mongol supremacy. In East Asia, there were a number of Mongol campaigns into Goryeo Korea, but Ögedei's attempt to annex the Korean Peninsula met with little success. Gojong, the king of Goryeo, surrendered but later revolted and massacred Mongol darughachis (overseers); he then moved his imperial court from Gaeseong to Ganghwa Island.
  
  In 1235, the Mongols established Karakorum as their capital lasting until 1260. During that period, Ogedei Khan ordered the construction of a palace within the surrounding of its walls.