Where did the Girgashites go?

Josh 12:8 "In the mountains, and in the valleys, and in the plains, and in the springs, and in the wilderness, and in the south country; the Hittites, the Amorites, and the Canaanites, the Perizzites, the Hivites, and the Jebusites"

Interesting that it leaves out one of the 7 nations often mentioned, the Girgashites (Gen. 10:16 and 15:21)