"Genghis Khan", born "Temüjin", was the founder and Khagan/Great Khan (emperor) of the Mongol Empire, which became the World's largest empires/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 the Mongol invasions that resulted in the conquest of most of Eurasia. These included raids or invasions of the Kara-Khitan Khanate, Caucasus, Mongol invasion of Khwarezmia/Khwarezmid Empire, Western Xia and Jin Dynasty (1115–1234)/Jin dynasties. These campaigns were often accompanied by wholesale massacres of the civilian populations – especially in the Khwarazmian dynasty/Khwarezmian and Western Xia/Xia controlled lands. By the end of his life, the Mongol Empire occupied a substantial portion of Central Asia and China.

More Genghis Khan on Wikipedia.

I am the punishment of God...If you had not committed great sins, God would not have sent a punishment like me upon you.

The Root of Wild Madder.

With Heaven's aid I have conquered for you a huge empire. But my life was too short to achieve the conquest of the world. That task is left for you.

The greatest happiness is to scatter your enemy, to drive him before you, to see his cities reduced to ashes, to see those who love him shrouded in tears, and to gather into your bosom his wives and daughters.

If my body dies, let my body die, but do not let my country die.

The greatest happiness is to vanquish your enemies, to chase them before you, to rob them of their wealth, to see those dear to them bathed in tears, to clasp to your bosom their wives and daughters.