In Judges 10:8, the Ammonites had already been oppressing Israel for 18 years — the same Ammonites Jephthah now confronts, providing immediate context.

Numbers 21:25-30 records Israel's conquest of Heshbon and the Amorite cities — the very territory Jephthah cites as Israel's possession for 300 years.

In Deuteronomy 2:36, Israel took this same territory (Aroer to Gilead) from Sihon — the land claim Jephthah now argues with the Ammonites.

Joshua 12:2 lists Sihon's territory including Heshbon, Aroer, and Arnon — precisely the cities Jephthah says Israel held.

Joshua 13:10 lists all the cities of Sihon king of Heshbon — the very territory Jephthah claims Israel possessed for 300 years.

Numbers 32:3 lists Heshbon and surrounding towns, the very places Jephthah says Israel inhabited for 300 years — a direct geographic link.

Deuteronomy 2:24 records God's command to take Sihon's land, initiating the possession Jephthah later references.

Deuteronomy 3:2 refers to Sihon of Heshbon — the Amorite king whose territory Jephthah claims Israel possessed.

Deuteronomy 3:6 mentions the destruction of Sihon's cities — the same conquest that gave Israel the cities Jephthah cites.

1 Kings 6:1 gives 480 years from the Exodus; Judges 11:26 gives 300 years from the conquest. Both provide chronological markers for Israel's history.