Can't figure out how trade through rivers works
I was watching serious trivia's kong rong early game guide (How to Get Started as Kong Rong | Early Game Legendary Difficulty Playbook Patch 1.7.0 - YouTube <- this one) and in it, after capturing the port settlement near kong rong's staring location he somehow gets trade with dong zhuo through the yangtze. However when I captured the settlement i couldn't trade with him, even though he had a port settlement, as well as a free trade route. Am i doing something wrong, or did ca change how you can trade with factions. If trading through rivers is not possible, then how are you supposed to play kong rong, when it is incredibly easy to get locked in a corner by tao qian and liu bei and you cannot even create many armies to expand properly since your economy relies on having as few armies as possible?
