Well, an
Himyarite-wank could do, as it was a
JEWISH arabic polity in south-west Arabia historically. IOTL it was crushed eventually by Axum (mostly on trade tensions rather than religious), but even without a PoD where Christianity doesn't devellops at the point it did in Romania, it's mostly savagable trough an Abyssinian
JEWISH dynasty (
Kingdom of Siemenl).
The main problem being the social-economic declie of Hiyarite Kingdom in the VIth century, that made it vulnerable to Axum in first place, and
JEWISH communities vulnerable to Persian then Islamic takeover in second place.
If it can be dealt with (a quicker Romano-Persian war, with a Persian defeat maybe), then you could end with a post-classical Himyarite hegemony maintaining its historical grasp (meaning South-East Arabia, plus southern-central Arabia.
With a
JEWISH Himyarite kingdom whom leader could be considered as Mukarrib of south Arabia, sky is not exactly the limit as you still would have to deal with Romans and Persians, but it's quite close already.