Born in Temujin, he was the founder and Great Khan (emperor) of the Mongol Empire, which became the largest contiguous empire in history after his demise. 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 invasions that resulted in the conquest of most of Eurasia. These included raids or invasions of the Kara-Khitan Khanate, Caucasus, Khwarezmid Empire, Western Xia and Jin dynasties. These campaigns were often accompanied by wholesale massacres of the civilian populations – especially in the Khwarezmian controlled lands. By the end of his life, the Mongol Empire occupied a substantial portion of Central Asia and China.
Before Genghis Khan died, he assigned Ögedei Khan as his successor and split his empire into khanates among his sons and grandsons. He died in 1227 after defeating the Western Xia. He was buried in an unmarked grave somewhere in Mongolia at an unknown location. His descendants went on to stretch the Mongol Empire across most of Eurasia by conquering or creating vassal states out of all of modern-day China, Korea, the Caucasus, Central Asian countries, and substantial portions of modern Eastern Europe, Russia and the Middle East. Many of these invasions repeated the earlier large-scale slaughters of local populations. As a result Genghis Khan and his empire have a fearsome reputation in local histories.
He also advanced the Mongol Empire in other ways. He decreed the adoption of the Uyghur script as the Mongol Empire's writing system. He also promoted religious tolerance and created a unified empire from the nomadic tribes of northeast Asia. Present-day Mongolians regard him as the founding father of Mongolia.