King of the Amorites: his history we have, Num. xxi. 21, &c. If the word be, as is supposed, its own root; it means rooting out.
King of the Amorites at Heshbon, on refusing passage to the Hebrews, and coming to attack them, was himself slain, his army routed, and his dominions divided among Israel, Num 21:21-34 Deu 2:26-36 .\par
Si’hon. (warrior). King of the Amorites, when Israel arrived on the borders of the Promised Land. Num 21:21. (B.C. 1451). Shortly before the time of Israel’s arrival, he had dispossessed the Moabites of a splendid territory, driving them south of the natural bulwark of the Amen. Num 21:26-29. When the Israelite host appeared, he did not hesitate or temporize like Balak, but, at once, gathered his people together and attacked them. But the battle was his last. He and all his host were destroyed, and their district from Amen to Jabbok became, at once, the possession of the conqueror.
King of the Amorites. Shortly before Israel’s approach he had dispossessed Moab of all their territory N. of Arnon. An Israelite poet celebrates Sihon’s victory, glorifying Heshbon as the city from whence "a flame" went forth "consuming Ar of Moab," so that "Moab’s sons their idol ("Chemosh") rendered fugitives, and yielded his daughters into captivity unto Sihon"! then by a sudden startling transition the poet introduces Israel’s triumph in turn over Sihon. "We ("Israelites") have shot at them, Heshbon is perished even unto Dibon, and we have laid them waste even unto Nophah, with fire even unto Medeba." Israel begged leave to pass peaceably through the Amorite land by the king’s highway, but "Sihon gathered all his people" and came to Jahaz (between Dibon and Medeba) and fought against Israel and was defeated. Churlishness and unprovoked violence bring their own punishment (Pro 16:18; Pro 18:12; Num 21:21-31). So Israel gained all the Amorite territory, from the Arnon to the Jabbok. Josephus says that every man in the nation fit to bear arms fought in the Amorite army against Israel (Ant. 4:, section 2). The struggle was a desperate one; no mere human force enabled Israel, heretofore unused to warfare, to subdue so formidable a king and conqueror as Sihon. Pride of conquest was his snare.
Sihon (sî’hon), sweeping away. A king of the Amorites at Heshbon, who was slain, and his kingdom taken by the Hebrews. Num 21:21-31; Deu 2:26; Psa 135:11-12; Jer 48:45.
[Si’hon]
King of the Amorites, who, after his victory over the Moabites, was defeated and slain, with his army, by the Israelites. His territory was on the east of the Jordan, from the Arnon to the Jabbok: it was possessed by the Israelites. The victory is commemorated in two of the Psalms. Num 21:21-35; Num 32:33; Deu 1:4; Deu 2:24-36; Deu 3:2-6; Jos 12:2; Jdg 11:19-22; Psa 135:11; Psa 136:19; Jer 48:45.
By: Emil G. Hirsch, Jacob Zallel Lauterbach, Wilhelm Bacher
—Biblical Data:
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).
—In Rabbinical Literature:
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).
SIHON.—A king of the Amorites at the time of the conquest of Canaan. His dominion lay beyond the Jordan, between Jabbok on the N. and Arnon on the S., extending eastward to the desert (Jdg 11:22). He refused to allow Israel to pass through his land, and was defeated at Jahaz (Num 21:21-24, Deu 2:26-36, Jdg 11:19-22). Heshbon, his capital, was taken; and his land, along with that of Og king of Bashan, became the possession of Reuben, Gad, and the half tribe of Manasseh. Frequent reference is made to his defeat (Num 32:33, Deu 1:4; Deu 3:2; Deu 3:6; Deu 4:46-47; Deu 29:7; Deu 31:4, Jos 2:10; Jos 9:10; Jos 12:2; Jos 13:10; Jos 13:21; Jos 13:27, 1Ki 4:19, Neh 9:22, Psa 135:11; Psa 136:19). Sihon in Jer 48:45 stands for Heshbon, the city of Sihon.
W. F. Boyd.