Numbers 32:33

And Moses gave unto them, even to the children of Gad, and to the children of Reuben, and unto half the tribe of Manasseh the son of Joseph, the kingdom of Sihon king of the Amorites, and the kingdom of Og king of Bashan, the land, with the cities thereof in the coasts, even the cities of the country round about.

Half the tribe of Manasseh. It is nowhere explained in the record how they were incorporated with the two tribes, or what broke this great tribe into two parts, of which one was left to follow the fortunes of its brethren in the settled life of the western hills, while the other was allowed to wander as a nomadic tribe over the pasture lands of Gilead and Bashan. They are not mentioned as accompanying Reuben and Gad in their application to Moses, neither were they included in his first directions (Numbers 32:25); but as they also were a people addicted to pastoral pursuit, and possessed as immense flocks as the other two, Moses invited the half of them to remain, in consequence, probably, of finding that this region was more than sufficient for the pastoral wants of the others, and gave them the preference, as some have conjectured, for their valorous conduct in the contests with the Amorites (cf. Numbers 32:39 with Joshua 17:1).