Numbers 32:33

And unto half the tribe of Manasseh... — This is the first mention of the tribe of Manasseh. The application for a grant of the land on the eastern side of the Jordan appears to have been made only by the tribes of Reuben and Gad. The explanation, however, of this mention of the half tribe of Manasseh is found in Numbers 32:39, from which it appears that a portion of that tribe had been chiefly, if not exclusively, engaged in the conquest of certain portions of Gilead and Bashan, and had, therefore, justly acquired a claim to the possession of the districts which they had subjugated. (See Deuteronomy 3:13.)