How do you know Arabs are not the children of Ishmael?
And Ishmael and his sons, and the sons of Keturah and their sons, went together and dwelt from Paran to the entering in of Babylon in all the land towards the East facing the desert. And these mingled with each other, and their name was called Arabs, and Ishmaelites.
—The before-Christ Jewish book of Jubilees 20:13
God promised the Middle-East (not just the approximate area of Israel) to Abraham's seed, and the Arabs fulfill that promise. God gave Ishmael's sons 12 nations, and there's no record of them ever being disbanded, as happened to the 12 nations of Jacob's sons.
That part is correct.
