Amoritic king of the east-Jordan country, whose kingdom extended from the Arnon in the south to the Jabbok in the north, and from the Jordan in the west to the desert in the east (Num. xxi. 24; Judges xi. 22). According to Josh. xii. 3 and xiii. 27, the Desert of Arabah, between the Jabbok and the Sea of Galilee, was included in Sihon's territory. His capital was Heshbon, which he had captured from the King of Moab (Num. xxi. 26). He was also the suzerain of Midian, the five Midianitish kings, finally slain by the Israelites (Num. xxxi. 8), being his vassals (Josh. xiii. 21). When the Israelites asked Sihon for permission to pass through his territory, he refused them, and collected an army at Jahaz, where he was defeated and slain by the invaders (Num. xxi. 21-25; Josh. xiii. 21; Judges xi. 19-22), who took possession of his kingdom. Sihon, like Og, King of Bashan, was considered a great and mighty monarch (Ps. cxxxvi. 17-19).
Sihon was the brother of Og, and both were grandsons of the fallen angel Shamḥazai (Niddah 61a). He resembled Og in stature and bravery (Midr. Agadah, Ḥuḳḳat, ed. Buber, p. 130a), and was identical with Arad the Canaanite (Num. xxi. 1), being called "Sihon" because he was like the foals in the desert for swiftness. He was termed also "the Canaanite" after his realm (R. H. 3a, where should be read on the basis of Num. xxi. 1), which included all Canaan; as he was monarch of the land he had vassal kings who paid him tribute. When the lsraelites asked permission to pass through his territory to enter Canaan, he said it was only to resist their attacks upon the Canaanite kings that he was in the land (Tan., Ḥuḳḳat, 52 [ed. Buber, p. 65a]).
If Sihon had retained his troops in the various cities of his realm, the Israelites would have been able to take them only with difficulty; but God caused the king to collect his whole army in his capital, and thus enabled the Israelites to conquer (ib.), although the city was so well fortified that Sihon had not been able to capture it from the King of Moab until he had called upon Balaam to curse the beleaguered army (Midr. Agadah, l.c.). Sihon could be vanquished only after God had subjugated his guardian angel to Moses (Yelammedenu, quoted in Yalḳ., Num. 764).