For 3 million years, the Central Americas isthmus has been both a barrier and a bridge, separating two vast oceans and connecting two huge continents. The northern areas of Central America were inhabited by the indigenous people of Mesoamerica. The most prominent of these were the Mayans, who had built many cities throughout the region. Before them, the Olmecs had rooted in many traditions and pyramids. The Olmec civilization, dating back to 1200 B.C. and perhaps earlier, is the mother culture of Mesoamerica. The Olmec roots are believed to have the early farming cultures of Tabasco, dating from 5100 BC to 4600 BC. Little is known about the Olmecs, and they remain a mysterious civilization. They are known to have laid many of the foundations for all subsequent Mesoamerican cultures, such as the Mayan and Aztec cultures. In Nahuatl, the language used by Aztec, they were called Ōlmēcatl. The word ōlli means “rubber” and mēcatl means “people”. Thus, the term can be translated as "rubber people".