According to Genesis 15:18-21 God promised the land of ten nations in the Middle East to Abraham and his descendants. Many believe all this land was for the Israelites, who came from Isaac and Jacob. However, in Exodus and Deuteronomy and other Bible books, the promised land of the Israelites is made up of the territory of only six of the ten peoples.
Apparently God also promised land to other descendants of Abraham. A careful study of the Bible shows that God also gave land to the Edomites, who descended from Isaac and Esau. According to Deuteronomy 2:9-11 en 3:11, God gave land of one of the ten people, the Rephaites, to the Ammonites and Moabites, who were the offspring of Abraham’s nephew Lot. This seems to contradict the promise that the land was given to Abraham’s descendants.
One could argue that only part of the land of the Rephaites went to Lot’s offspring and that the rest did end up in the hands of Abraham’s clan. However, Ezekiel 25:1-10 offers a better explanation. There it says that God would give the land of Ammon and Moab as a heritage to the people of the east. These were Ishmaelites and direct descendants of Abraham. So, centuries later God’s promise to Abraham came true after all.
For an in-depth study, go to Study Land for the Arabs