By the first millennium, South America's vast rainforests, mountains, plains, and coasts were the home of millions of people. Estimates vary, but 30–50 million are often given and 100 million by some estimates. Some groups formed permanent settlements. Among those groups were Chibcha-speaking peoples ("Muisca" or "Muysca"), Valdivia, Quimbaya, Calima, Marajoara culture and the Tairona. The Muisca of Colombia, postdating the Herrera Period, Valdivia of Ecuador, the Quechuas and the Aymara of Peru and Bolivia were the four most important sedentary Amerindian groups in South America. From the 1970s, numerous geoglyphs have been discovered on deforested land in the Amazon rainforest, Brazil, supporting Spanish accounts of a complex, possibly ancient Amazonian civilization.