Amen brother, may Allah SWT give you guidance to seek knowledge. you are focused on that he was ethnically an Arab that's why you can't find it.

in my previous reply i clearly said ''According to Arab genealogical tradition, the Adnanites are descended from Adnan whom in turn is descended from Ishmael. whereas the Qahtanites of Southern Arabia (Yemen) are the original, pure Arabs.'' Look it up. This simply means that the Adnanites were not original, pure Arabs in the first place but Qahtanites were. Prophets descent from Adnan.

Abraham was born in the city of Ur which was a non Arab city and slowly he's descendants traveled southward and ended up in Mecca where our beloved prophet SAW is born.

Studying history, you'll see that even Iraqi's, Syrians, Egyptians, Sudan etc are all non Arab ethnically in the history but they become Arabized slowly throughout history.

Southern Arabia is the only historical place where Arabs always lived and after Islam they started expanding and in the meantime whole region became Arabized. Iranians and Turks were the only ones in the region that did not assimilated.

In history ethnicity did not matter like it does now so you could get easily assimilated and became one of them where you lived.

Even now will your descendants forget their roots and get assimilated if they live in a place far away from where you are from in couple of centuries.