Based on artifacts found in the region, apparently hunting of guanaco, and to a lesser extent rhea (ñandú), were the primary food sources of tribes living on the eastern plains.[1] Whether the megafauna of Patagonia, including the ground sloth and horse, were extinct in the area before the arrival of humans is unclear, although this is now the more widely accepted account. It is also not clear if domestic dogs were part of early human activity.