The Eastern Agricultural Complex was one of about 10 independent centers of plant domestication in the pre-historic world. By about 1,800 BCE the Native Americans (Indians) of North America were cultivating for food several species of plants, thus transitioning from a hunter-gatherer economy to agriculture. After 200 BCE when maize from Mexico was introduced to what is now the eastern United States, the Indians of the present-day United States and Canada slowly changed from growing indigenous plants to a maize-based agricultural economy. The cultivation of indigenous plants declined and was eventually abandoned, the formerly domesticated plants reverting to their wild forms.