There have been different a lot of powerful rulers who have conquered the world. Some like Alexander the Great conquered the one-third of the earth, king Xerxes that ruled over Asia to Africa. But the most valiant and the one often referred to as the greatest conqueror of all is the Emperor Genghis Khan.
Emperor Genghis Khan was the first Great Khan and founder of the notable Mongol Empire which later became the largest empire in history after his death. The Great Khan rose to power by uniting the nomadic tribes of Northeast Asia. He then started Mongol invasions that conquered most of Eurasia.
Genghis Emperor was the founder and first Great Khan and Emperor of the Mongol Empire, which became the largest contiguous empire in history after his death. He came to power by uniting many of the nomadic tribes of Northeast Asia. After founding the Empire and being proclaimed Genghis Khan, he launched the Mongol invasions that conquered most of Eurasia (the then combination of Europe and Asia).
Campaigns launched by Khan were often accompanied by a large massacre of civilians. Because of the loss of lives associated with his campaign, he is often referred to by many as a brutal ruler. Towards the end of his reign, his kingdom had occupied most of the landmass in Central Asia and China. He is often known as the greatest conqueror due to his exceptional military accomplishments.
His third son Ogedei Khan was appointed by him as a successor before his death in 1227. Later on, his kingdom was split by his grandsons.