Yep, I need to also work on sea migrations to handle situations like that. Because sea migrations can speed up colonization a lot, but they are also very dependent on technology and external factors like ocean currents. For example, the Polynesians were able to colonize many distant islands because they mastered boatbuilding and navigation at a very early stage, but they preferred navigating against the current to ensure that their failed exploration voyages could be returned from. I would need to take into account stuff like that in my model.