Slop.

I read "Indigenous Continent" recently, and it really drove home the point that the settlers couldn't even identify land that was being used productively by Native Americans. They'd stumble upon carefully managed forest gardens and crop fields, and just go "look at all this completely unused land", simply because it did not look like European farm land. The early settlers were at a complete loss as to how indigenous people were feeding themselves whilst the settlers were themselves starving to death. It went beyond animal husbandry. They wouldn't see neat rows of plowed fields with the same crop row after row and go, damn looks like nothing is here.