“Adjoining the territory
Of Zebulun,
From the east side
To the west side,
Gad shall have
One portion.”
Gad was originally on the east side of the Jordan River in Joshua, chapter 13. They were originally surrounded by Manasseh on the north and west side, with Reuben to its south. It was never close to Zebulun. However, both might have been small tribes by this time.
Eugene Finnegan Bible Project 