I'm writing a story about Earth before the industrial revolution, but without continents, where all the countries are placed on separate islands, and all of them are extremely isolationist and xenophobic. They kill any foreigners that steps on their land, and the navy sinks foreign ships sailing near their coast. Any citizen that leaves their home country or has a relationship with a non-citizen becomes rootless.
The trade between countries is done by these rootless, who are allowed to dock in designated ports, and trade their goods. Each country allows only short stays. Rootless are not allowed to buy property, and leaving the gateway port or overstaying means swift death. If a child is born from a rootless parent it becomes rootless itself.
I'm having trouble how would their culture look like? Especially how would women & young children survive if they have to move constantly.
The closest thing I could find in our world are Moken