The history of Peru spans several millennia, extending back through several stages of cultural development in the mountain region and the coastal desert. About 15,200 years ago, groups of people are believed to have crossed the Bering Strait from Asia and survived as nomads, hunting, gathering fruits and vegetables and fishing in the sea, rivers, and lakes. Peruvian territory was home to the Norte Chico civilization, one of the six oldest in the world, and to the Inca Empire, the largest state in Pre-Columbian America. It was conquered by the Spanish Empire in the 16th century, which established a Viceroyalty with jurisdiction over most of its South American domains. The nation declared independence from Spain in 1821, but consolidated only after the Battle of Ayacucho, three years later. This is essentially a foundation article for the discussion of artifacts that will follow.