The Olmec Civilization

The Olmec Civilization was centered in southern Mexico. They began to rise around 1150BC and slowly disappeared around 900 BC. Their most known vestiges include the gigantic heads which can be found around San Lorenzo Tenochtitlan.

The Olmecs lived in what we know now as the State of Veracruz, around the town of San Lorenzo. It is believed that the rich soil of that area allowed abundant harvests, thus large groups of nomads settled and eventually developed a civilization. The first settlements date back to 1150 BC. The Olmecs rapidly extended as far as the State of Guerrero and Tabasco. They are considered as the mother of later civilizations including the Maya and the Aztecs.

The Olmecs were the first civilization to create a complete writing system, using hieroglyphics, the earliest known example dating from 650 BC. They also had their own mathematical system, based in the number 20 which was adopted, developed and perfectioned later by the Maya.

Olmec main cities were San Lorenzo, La Venta and Laguna de los Cerros. They traded among them since each one is located near different resources. San Lorenzo is next to a large fertile plain area close to rivers that they used as trade routes. La Venta is on the coast and provided cacao, rubber, and salt. Laguna de los Cerros is near a major source of basalt, a stone they used extensively to create their monuments.

Vestiges show that buildings, and cities in general, were built with clear orientation intention. This characteristic was later inherited by all the civilization in Mesoamerica. Clay was the most common of the materials they used to build, that's the reason why there are not many visible buildings left.
Some suppose the Olmecs didn't disappear all of a sudden as many other civilizations, on the contrary they were absorbed little by little by rising civilizations such as Zapotecs and Mayas.