The Atapuerca Mountains (Sierra de Atapuerca in Spanish) is an ancient karstic region of Spain, in the province of Burgos, Castile and Leon and near Atapuerca and Ibeas de Juarros. It contains several caves, where fossils and stone tools of the earliest known Hominins in West Europe have been found, belonging to the species Homo antecessor (or Homo erectus antecessor) and Homo heidelbergensis. The earliest hominids may have dated to 1.2 million years ago, representing the first in Western Europe.