Mizpah means a station or place from which watch can be kept; something like a watchtower. In the Old Testament, the name does not always refer to the same place. Most familiar is Mizpah in Benjamin, a political and religious center west of the Jordan (for example, Judges 20:1–48 and Judges 21:1–25; 1 Samuel 7:10). Here we have Mizpah in Gilead, east of the Jordan, also mentioned in Genesis 31:49. Apparently it had some prominence; maybe it was a kind of sanctuary.
11 So Jephthah went with the elders of Gilead, and the people made him head and leader over them. And Jephthah spoke all his words before the LORD at Mizpah.