Might I chip in an outsider option and say "give it all to the Aedui"? I mean everything, not just Gaul. It could make for an *cough* interesting situation...

Otherwise, listen not to foul-mouthed heretics such as Aaldaemon. The Saka are your friends. They wish you well. You want to give them that land. You have to. It's your duty as a Strategos.