Factions aren't yet fully released, but the devs had to put them geographically on the map and provide information about them ingame (eg description and standings on the faction page) otherwise people would mightlily complain when they suddenly found their nice new city was actually next to the flesh-eating-zombie faction! I know I would.
ie, Factions are on the map, and they have trade hub locations that they own that you can see on the World Map - but there is currently no way of interacting with them.
A useful post from the devs as follows:
^^ Outlines the plans for factions and what they will do in the future