He defeated many nations and killed powerful kings.
But the Israelites defeated the king and took his land from the Arnon River to the Jabbok River. The Israelites took the land as far as the Ammonite border. They stopped at that border because it was strongly defended by the Ammonites.
So the Israelites defeated Og and his army. They killed him, his sons, and all his army. Then the Israelites took all his land.