My plan is to somehow get the Arabs converted to a sect of Judaism in the 6th or 7th century (anno domini), and then have their population explosion spread it across the Middle East, with Arabic being the "low" language, and Hebrew being the "high" language. This is challenging to not do in a ridiculous way, but not impossible.
What I need is for the conversion to take place. Judaism is not an inclusive religion, but it is by no means unheard of for people to convert anyway. Look at the Khazars. Anyway, wasn't there some kind of weird Ethiopian Jewish state in Yemen? Himyar, wasn't it?
Is it as easy as having an influential prophet appear? I mean if I time it right the Arabs demographic expanision will still occur.