The Bible describes that as the Israelites in their Exodus came to the country east of the Jordan, king Sihon of the Amorites refused to let them pass through his country. The Israelites fought him in a battle, gaining complete victory. Sihon and his sons were put to the sword, his walled towns were captured and the complete Amorite country was taken by the Israelites. (Num. 21:21-30, Deut. 2:24-37).
In a similar way the Israelites took the country of Og, and these two victories gave them possession of the complete country east of the Jordan, from the Arnon to the foot of the Hermon.
Numbers 21:35 So they smote him, and his sons, and all his people, until there was none left him remaining; and they possessed his land.
These victories, among the earliest successful campaigns of the Israelites, quickly became legendary among them, and are referred to numerous times in the Bible as prototypical examples of god-given victory.
In accordance with his celestial origin Sihon was a giant who none could withstand, for he was of enormous stature, taller than any tower in all the world, his thigh-bone alone measuring eighteen cubits, according to the big cubit of that time.
Sihon's answer therefore was as follows: "I and my brother Og receive tribute from all the other Canaanite kings to keep off their enemies from access to the land, and now you ask me to give you free access to Canaan!"
Sihon and his son, who equaled him in heroic strength, found their death in this fray.
The whole country on the east of Jordan, from the Arnon to the Jabbok, was possessed by the Amorites, whose king, Sihon, refused to permit the Israelites to pass through his territory, and put his army in array against them.
The Amorites were defeated; Sihon, his sons, and all his people were smitten with the sword, his walled towns were captured, and the entire country of the Amorites was taken possession of by the Israelites (Num.
The country from the Jabbok to Hermon was at this time ruled by Og, the last of the Rephaim.