“To the Merarites according to their families were allotted twelve towns out of the tribes of Reuben, Gad, and Zebulun.”
Merari was the 3rd son of Levi who received 12 towns on the east side of the Jordan River. Somehow Zebulun was included with this group, but they were on the west side of the Jordan. Once again, there is no mention of their names as in Joshua, chapter 21.