After I just realized that you need a minimum of five people to form a tribe, I'm actually disappointed. In my opinion, you should have a minimum of at least two or three players if anything. Like come on, even on Wurm Online you're able to build anywhere you'd like without a deed.
You shouldn't force players to group up, great way to lose em. Could be one of the reasons that Wurm Online isn't successful. Soloing should also be an option. If I were to bring in two of my friends, I would still have to look for two more players. The limit seems too high for players who only wanna team up with their friends. You also require many gaming friends in order to create your own tribe. Not the greatest way to encourage a player to advertise.