The Manasseh (tribe) was one of the 12 tribes of Israel. A son of Joseph named Manasseh founded the tribe, and it formed the House of Joseph together with the Tribe of Ephraim. Joseph himself was a son of Jacob. The tribe of Manasseh and the tribe of Ephraim are the only two tribes that don't have Jacob as their father.
The Manasseh tribe occupied the territory on both sides of the Jordan River, with a half-tribe on each side.