Then the Israelites sent messengers to Sihon the Amorite king:
References for Numbers 21:21
"Let us pass through your land. We won't turn aside into a field or vineyard. We won't drink water from a well. We will walk on the King's Highway until we cross your border."
But Sihon wouldn't allow the Israelites to cross his border. Sihon gathered all his people and went out to meet the Israelites in the desert. When he came to Jahaz, he attacked the Israelites.
The Israelites struck him down with their swords and took possession of his land from the Arnon to the Jabbok, as far as the Ammonites, for the border of the Ammonites was fortified.
The Israelites took all these cities. Then the Israelites settled in all the cities of the Amorites, in Heshbon and all its villages.
Now Heshbon was the city of Sihon the Amorite king who had fought against the former king of Moab. He had taken all his land from him as far as the Arnon.
Therefore, the poets say: "Come to Heshbon, let it be built. Let the city of Sihon be established.
Fire went out from Heshbon, flame from Sihon's city. It consumed Ar of Moab and swallowed up the shrines of the Arnon.
You are doomed, Moab! You are destroyed, people of Chemosh! He gave his sons as fugitives, and his daughters as captives to the Amorite king Sihon.
Yet we have thrown them down, destroying them from Heshbon to Dibon. We brought ruin until Nophah, which is by Medeba."
References for Numbers 21:30
Israel settled in the land of the Amorites.
Moses sent spies to Jazer. They captured its villages and took possession of the Amorites who were there.
Then they turned and ascended the road of Bashan. Og, Bashan's king, came out at Edrei to meet them in battle, he and all his people.
The LORD said to Moses: Don't be afraid of him, for I have handed over all his people and his land. Do to him as you did to Sihon the Amorite king who ruled in Heshbon.
They slaughtered Og, his sons, and all his people until there were no survivors. Then they took possession of his land.