It would be nice to have conditional spawns, like DOC does IIRC, for civs like the Byzantines, Sassanids and possibly some others (I was thinking of Palmyra under Zenobia). Otherwise you have some civs that essentially spawn on top of other civs (e.g. Sassanids on top of Persia) and others that have cores that make them too small to survive (e.g. Byzantines). It might be technically difficult though.