The children of Merari by their families had out of the tribe of Reuben, and out of the tribe of Gad, and out of the tribe of Zebulun, twelve cities. (Joshua 21:7)
Merari was the youngest son of Levi and was the last to receive his cities. His descendants were the smallest in number, so he received only 12 cities, 8 of these being east of the Jordan.