Gateways are a gate system linked to a Corridor which connects different part of the world and it is also connected to another worlds. It is used to travel around the world or to other world in Suikoden Tierkreis.
The Wanderers use the gateways to travel back and forth from their country to another country and from their world to another world.
When The One King was defeated, the gateways cannot connect to another world anymore due to the fact that The One King is the one who connect the gateways from world to world.