It is almost certain that the Americas were peopled by migrations from northeast Asia, but the timing of such migrations remains uncertain. They likely began at least 25,000 years ago. It is also difficult to estimate the population of the Americas before contact with Europeans. Estimates range from 37 million to 100 million. It is clear, however, that the vast majority of people lived within a few hundred miles of the equator, and the smallest number—perhaps 4 to 7 million—lived in present-day North America. By the fifteenth century, like other regions of the world, the Americas were home to diverse societies, ranging from coastal fishing villages to nomadic hunter-gatherers to settled horticulturalists to large city-centered empires.