Deuteronomy 2:17-21

that the Lord spoke to me, saying,

‘Today you shall cross over Ar, the border of Moab.

When you come opposite the sons of Ammon, do not attack them nor provoke them, for I will not give you any of the land of the sons of Ammon as a possession, because I have given it to the sons of Lot as a possession.’

(It is also regarded as the land of the Rephaim, because the Rephaim previously lived in it, but the Ammonites call them Zamzummin,

a people as great, numerous, and tall as the Anakim; but the Lord destroyed them before them. And they dispossessed them and settled in their place,