Sea Region is the ocean. The second sea region in M2TW is probably the deep waters regular ships cant sail on.
As for factions...well we try to choose primarily factions with historical merit. But we can always choose some factions who either sat in their forests and didn't do much when it came to military expansion, or had a different skin color than the rest. Maybe even include a faction which would only be in one province, but who happens to worship a god that is worshiped today.
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