@setsu The Varangian goes Praetorian I guess. There doesn't seem to be the famous Constantinople's walls too, so it's either that or they might never exist at all.
Yeah, "turks" are too loose of a term so I'm not really sure which one is which too here honestly. Some of these might be wrong, but I guess I'll use the Seljuks and the Ottomans as (even though the latter only come later on). ---All I know is that it's not instant, but they seem to start off as mercenaries under a the Abbasid Caliphate, then many start migrating to the middle east since I guess it's easy to reach and they have a decent foothold for relationship already, and later start becoming the main character in the overall story.
Not exactly quick, yeah, but I think becoming a mercenary there is the perfect prologue for all that.
About Hannibal, I'm talking more about the infantry. If I'm not mistaken, Carthage in the first Punic war relies heavily on mercenaries for wars, and later after they lost the mercenaries start rebelling 'cause they didn't get paid, but they still kinda like Hasdrubal (Hannibal's father, play a big part during the war) and later start changing from mercenary to Hannibal's sort-of private army, loyal more to him than the senates. The cavalry is from Iberia/Spain, but most the infantry doesn't (I think).