The word khan is not a name, but a title. It means chieftain or king. It is a word used in various forms by the different tribes and nations that from time immemorial have inhabited Central Asia, and has been applied to a great number of potentates and rulers that have from time to time arisen among them.
Genghis Khan was the greatest of these princes.
He was, in fact, one of the most renowned conquerors whose exploits history records.