Which khan founded the Mongol Empire?

Genghis Khan, born Temujin, who united the steppe tribes and built the largest contiguous land empire in history - and did it after a childhood in which his father was poisoned, his family was abandoned by their clan to starve, and he was captured and enslaved by rivals.

The army was a meritocracy in a world of aristocracies. He broke up tribal units and reorganised the entire force by decimal groups mixing origins, promoted commanders on ability including former enemies, and made loyalty to himself the only line that mattered. He also instituted a written legal code, religious tolerance across the empire, diplomatic immunity, and a postal relay system with stations every 40 kilometres that could move a message across Asia in weeks.

The killing was on a scale that shows up in the climate record. Estimates of deaths in the conquests run to tens of millions, some regions were depopulated for centuries, and there is a serious argument that the resulting reforestation of abandoned farmland pulled enough carbon out of the atmosphere to be measurable. His grave has never been found - the burial party was reportedly killed to keep the location secret, and Mongolia has generally discouraged searching for it.