The Olmec civilization is known as the Mother Culture. The Olmec are the oldest civilization known in our history. Our Old Grandparents established themselves before Christ, but the Olmec are considered to be our great-grandfathers. Their culture emerged between the states of Veracruz and Tabasco. This civilization grew and expanded throughout Mesoamerica. It is believed the Olmec invented a system to measure time that consisted of three exact and perfect calendars. The first consisted of 260 days based on lunar observations. The second calendar of 365 days was based on the movement of the earth around the sun, and the third had 52 years that was based on the observations of the earths movement in relation to the stars and constellations, known as the Pleiades. Even today, 4,000 years later, their accurate calendars are a source of wonderment because the Olmec knew how develop and use the system. Their superb knowledge in mathematics is evident in the architecture of pyramids, plazas and temples that also demonstrate their knowledge in astronomy for their buildings are precisely aligned with the four cardinal points. In Oaxaca, like in the rest of Mexico, there is ample evidence all significant cultures were influenced by the Olmec. A vivid example is the Dancers of Monte Alban. These magnificent engraved stones depicting deformed human beings show Olmec influence. The Olmec culture left evidence of their existence in the form of gigantic stone heads with Negroid features wearing helmets. The Olmec - People of the Rubber - knew how to use this product in the balls used in their games and other various forms. Their most famous archaeological sites are found in La Venta and Comalcalco in Tabasco; San Lorenzo, Tres Zapotes and Catemaco in Veracruz, Oxtotitlan and Zumpango del Rio in Guerrero, Monte Alban and Huamelupan, in Oaxaca, Uaxcatun in Quintana Roo and Chalcatzingo in Morelos.