The Mongols besieging themselves CTD

[Imperial Glory]

So, I was playing as the Khwarizmi, just screwing around when I decided to negotiate with the Mongols on the first turn. I manage to get a ceasefire by giving them Khiva and Konjikala plus my entire treasury and some trade rights, before ending my turn. Them besieging those settlements appears to be scripted as they promptly besieged their own garrison, I merge the two garrisons from the two settlements, happy that i saved my Shah before ending my turn. The game promptly CTD. suggestions why this happened are welcome

[Imperial Glory]

nevermind thees another thread on this