The answer is "plowed fields and domesticated bulls" Before the appearance of white European settlers in North America, there was limited agriculture practiced by the Native Americans, certainly nothing to the scale of the contemporary Europeans at the time. The same goes with domestication of animals, which was practiced on a much smaller scale by the pre-Columbian Natives. Indeed, many Europeans justified simply taking Native American territories because they weren't "being utilized" in the practice of growing crops; the notion was that whomever "made the land useful" had clear right to it.