Are you sure?But that's not overseas trade.
Custom houses are Foreign trade, not Overrseas trade
(Over seas trade you can have with yourself... some use to all those one tile islands... settle one and ALL of your cities can get an overseas trade route with it)
Interesting, I didn't know that. That would mean that vassal trade isn't foreign trade even with, say, FM.Yeah exactly. Trade with vassals isn't foreign trade.
Custom houses are Foreign trade, not Overrseas trade
(Over seas trade you can have with yourself... some use to all those one tile islands... settle one and ALL of your cities can get an overseas trade route with it)
But vassals are permanent allies!