He came to power by uniting many of the nomadic tribes of northeast Asia. After founding the Mongol Empire and being proclaimed "Genghis Khan", he started the Mongol invasions and raids of the Kara-Khitan Khanate, Caucasus, Khwarezmid Empire, Western Xia and Jin dynasties. During his life, the Mongol Empire eventually occupied a substantial portion of Central Asia.Before Genghis Khan died, he assigned Ogedei Khan as his successor and split his empire into khanates among his sons and grandsons. He died in 1227 after defeating the Tanguts. He was buried in an unmarked grave somewhere in Mongolia at a location unknown. His descendants went on to stretch the Mongol Empire across most of Eurasia by conquering and/or creating vassal states out of all of modern-day China, Korea, the Caucasus, Central Asian countries, and substantial portions of modern Eastern Europe and the Middle East.