This was Israel’s second stay at Kadesh, in the fortieth year of their wilderness wanderings (Numbers 20:1, Numbers 20:14; see also Deuteronomy 1:45; Deuteronomy 2:1, Deuteronomy 2:14). This was where Israel first emerged from the desert and journeyed to the southern outskirts of the Promised Land (Deuteronomy 1:19). But Israel failed to enter the land at the time, and withdrew into the Sinai desert again, only to come back to Kadesh forty years later. This is the stay that Jephthah is referring to.1
16 but when they came up from Egypt, Israel went through the wilderness to the Red Sea and came to Kadesh.