He was given the name of Temujin which means "iron worker." He didn't become Genghis Khan until the age of 21; "Khan" being a title for a leader, and "genghis" probably referring to his prowess as a leader.
What Is Genghis Khan's Birth Name?
Temujin his name was not Genghis Kohn until he turned 21. He was named for being the leader or commander