One thing that also happens is that the longer you keep an alliance, the better relations you'll have, and the less likely it is for the alliance to be broken. There's a good possibility that because the Pahlava remained allied to the AS for so long, that their poor starting relations have improved to the point that they may no longer be interested in attacking them at all.

I doubt the Saka are much of a factor at the moment. The Pahlava and Saka start out being really close allies, and that only improves with time. I've almost never seen them at war, at least not any time in the early game.