to a cultural region known as Mesoamerica, which roughly corresponds to central Mexico on into Central America, encompassing three thousand years from 1500 BCE to 1500 CE generally divided into three eras: Pre Classic, Classic and Post Classic. The first dominant Mesoamerican culture was that of the Olmecs, which peaked around 1200 BCE. The Olmecs originated much of what is associated with Mesoamerica, such as hieroglyphic writing, calendar, first advances in astronomy, monumental sculpture (Olmec heads) and jade work. They were a forerunner of later cultures such as Teotihuacan, north of Mexico City, the Zapotecs in Oaxaca and the Mayas in southern Mexico, Belize and Guatemala. While empires rose and fell, the basic cultural underpinnings of the Mesoamerica stayed the same until the Spanish conquest of the Aztec Empire. These included cities centered on plazas, temples usually built on pyramid bases, Mesoamerican ball courts and a mostly common cosmology. While art forms such as cave paintings and rock etchings date from earlier, the known history of Mexican art begins with Mesoamerican art created by sedentary cultures that built cities, and often, dominions. While the art of Mesoamerica is more varied and extends over more time than anywhere else in the Americas, artistic styles show a number of similarities. Unlike modern Western art, almost all Mesoamerican art was created to serve religious or political needs, rather than art for art's sake. It is strongly based on nature, the surrounding political reality and the gods. Octavio Paz states that "Mesoamerican art is a logic of forms, lines, and volumes that is as the same time a cosmology." He goes on to state that this focus on space and time is highly distinct from European naturalism based on the representation of the human body. Even simple designs such as stepped frets on buildings fall into this representation of space and time, life and the gods. Art was expressed on a variety of mediums such as ceramics, amate paper and architecture. Most of what is known of Mesoamerican art comes from works that cover stone buildings and pottery, mostly paintings and reliefs. Ceramics date from the early the Mesoamerican period. They probably began as cooking and storage vessels but then were adapted to ritual and decorative uses. Ceramics were decorated by shaping, scratching, painting and different firing methods. The earliest known purely artistic production were small ceramic figures that appeared in Tehuacán area around