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My progress so far. Saka had Marakanda, so I had to start warring with them early. I'm still allied to the AS, and hopefully will be until I decide to start conquering them. That rebel stack in my northeast looks menacing, but I'm on M/M, so they won't attack, and they're actually good for keeping the Saka away from that border. It's kind of exploiting the difficulty, but whatever. I'm going strike at the Saka first and try to stop them before they get any momentum going. I'm saving up for a mine in Kophen and the other town, so that'll ease my upkeep costs as soon as I get them online.

I don't really want to completely conquer Saka and the Parthians, but I think you're right. If I let them be, I'd have to keep my northern borders heavily garrisoned which would only eat away at my mnai, which I can't really afford. I think for my larger conquest, I'll have a main royal army led by Diodotus Jr., then have two cheaper armies. That way, I can have Diodotus around for all the important battles, and have the cheaper armies stick around and mop up any remnants and take the towns with smaller garrisons. Diodotus would have to take all the important towns, like Seleukeia, Antiocheia, Alexandreia, etc.

It should be relatively easy if I go quick enough.