The tribes that settle to the east of the Jordan

In Numbers 32 half of the tribe of Manasseh, the tribe of Reuben and the tribe of dan ask to settle on the east side of the Jordan, outside the Promised Land (32:5).

Moses is initially worried that this will discourage the rest of the tribes from entering the Promised Land.  But they assure Moses that they will send their fighting men with the other tribes to conquer Canaan.