Well Old Guy, I'm an old guy too. I believe your question was "Who came first? The Arabs or the Jews?" The most ancient source of information on this question is the Torah or the Christian's Old Testament. The father of both was a man from Ur of the Chaldees (roughly modern day Iraq) whose name was Abram. The story starts in the Book of Genesis, I believe Chapter 11. God told him to pack up and move out to a land that He would show him. His household and his nephew Lot went with him and they eventually arived at the land of Canaan. Because he was faithful in his response to God's direction God made a promise to him. He told him that He would give him a son by his wife Sarai. If you read through this section you'll see that I am skipping a lot of detail that is important but I am trying to get to your specific question. In his old age Abraham (note the name change) began to doubt and probably thought (along with his wife Sarah[note again a name change]), that maybe God needed a little help. This is what one would call a "lack of faith". Abraham took Sarah's servant Hagar as a concubine and had Ishmael, the father of the Arabic peoples. Hagar is considered to have been an Egyptian by many scholars. God's promises also extended to Ishmael as he was Abraham's firstborn but he was not the child of faith nor was he the child of Sarah. If I remember right Ishmael was about seventeen when Isaac ("Laughter" because Sarah had laughed in disbelief at God's promise) was born. Sarah then desired to drive Hagar and Ishmael from the camp, which she did. A prophecy was made concerning Ishmael that he (and his decendants) would be a wildman and that everyman's hend would be against him and his hand against every man. The answer is that the Arabs came first. The Jews are descendants of Judah, one of the 12 (or 13) children of Jacob.

An interesting sidenote to this is that when Moses went out into the desert in exhile he came into an Arab settlement (the Middianites) and married a Middianite woman. It was the Middianite's God who called to him from the burning bush and eventually revealed Himself as the I AM (YHWH). In the King James and most English Bibles where the name LORD all in caps appears the Hebrew word is YHWH and where God appears the word is Elohim (the Strong One). El is suffixed into many Hebrew names ( Isra el, Jo el, Micha el, etc.) as an honorific to the diety. Yah is prefixed into names as a specific honorific to YHWH.

Time and space do not allow for a full exposition of the failures of the Hebrew/Jewish people nor the failures of the Arabs nor the failures of those who go by the title of Christian but there is plenty of blame to go around but I dare say that Judasim, Christianity and Islam all have preachments which allow for the peaceful co-existence (or tri-existence) of these children and adopted children of Abraham.