The Tribe of Manasseh received half of their inheritance on the east of Jordan; their brothers, the rest of the tribal clans of Manasseh received their inheritance, by lot, on the Western side of Jordan. The two halves, each on either side of Jordan, together make up the Tribe of Manasseh.

Gideon was of the tribe Manasseh (sp) Pronounced Man- nas-suh.

The tribe of Manasseh was split into two half-tribes because when Moses allocated land to the Israelite tribes, the eastern half of Manasseh requested to settle on the east side of the Jordan River due to their large herds of livestock. This division allowed them to have land suitable for their needs while still remaining part of the tribe of Manasseh.

Joseph made both of his kids tribes of their own, hence

Ephraim is the 13th tribe, but a whole tribe not a half.

The smallest tribe was Manasseh according to the first census taken by Moses and Aaron in Numbers chapter 1.