The white people of the village were having an extremely difficult time living there when winter came. They didn't know what to do and weren't used to the land there. They were starving and freezing and didn't know what to do. So a nearby Native tribe met with them and offered to help them and teach them how to live, and the white villagers all went to live with the natives. That native tribe in that area has since had some white european DNA in them, because the white people there were completely integrated and mixed into their tribe's family. So the villagers carved Roanoke on the tree right before they left so it would tell anyone who comes looking for them where they went to. They went to Roanoke, the nearby place where that native tribe lived, to go live with them. I forget what Croatoan means and I don't want to spend any time to look it up, but maybe that is the name of the tribe.