Zebah and Zalmunna seem to have fled nearly due east to Karkor, which was probably an enclosure of some kind (perhaps a walled sheepfold, compare Numbers 31:32 note). Its site is unknown; but it was near Nobah, in the half-tribe of Manasseh in Gilead Numbers 32:40, and Jogbehah was in the tribe of Gad Numbers 32:34-35. Gideon, perhaps taking a circuit so as to come upon them from the east, fell suddenly upon them, apparently at night, surprised them, and smote them.
Related Commentaries of Judges 8:10
Judges 8:10
10 Now Zebah and Zalmunna were in Karkor, and their hosts with them, about fifteen thousand men, all that were left of all the hosts of the children of the east: for there fell an hundred and twenty thousand men that drew sword.