Why was Kang exiled?

This question is sort of alluded to in the film but never directly addressed. Basically, this Kang—the Conquerer—looked at the end of time and saw something he didn’t like. “A lot of me,” he puts it. And so, to stop that from happening, he began to destroy various timelines until he was stopped by the other Kangs, who didn’t like that he was messing with their plans. But how many did he kill? How long was he doing it? We don’t know.