Hi, this is maybe a bigger thing to do. But since there should be more interaction with your surrounding in future.
How would it be if there were some kind of preferred traveling routes where you can embark like on a river. When you embark on such a location, more merchants want to travel through your map and even armies or maybe some traveling heroes, moving between cities so you can set up taverns, or block the rout and collect taxes.
These routes could also be more dangerous, since you got more merchants. I think it would give reason to build cool big walls or castles and some protected passage.