The difficulty for me with Hayasdan in the two campaigns I tried was that though you can own the AS easily as long as you are using many of your family members (I only had them to worry about as I was allied with Pontos and Sauromatae), you have the classic problem of the Salient. The deeper you expand into AS territory the more bloated your salient becomes, and the longer the front on which the enemy can attack you. Not to mention there aren't any more mountains or valleys to protect you.

That, and you have the two giants ingame to worry you. After taking Antiocheia and Damaskos to remove one of the three fronts the AS could counterattack me on, the Ptolemaioi did the unthinkable and signed alliance with the AS, attacked me, and got me embroiled in an escalating struggle in Antiocheia. Meanwhile the AS attacked from the east towards Arbela, with nothing to even stop them. It was very nasty work, and I quit after I spied another 2 Ptolemaioi fullstacks headed for me. This was in the first 30 years.