Gradually, the richer, more powerful samurai families realized just how weak the emperor really was. There was on reason why they should do what he wanted any more.
So, instead of defending the emperor, they started fighting each other, to acquire land and power for themselves. Each samurai family, or clan, was ruled over by a local lord, also known as a warlord. By the 12th century, there were lost of these
Clans all over Japan and they fought almost constantly.