The Preclassic period in Maya history stretches from the beginning of permanent village life c. 1000 BC until the advent of the Classic Period c. 250 AD, and is subdivided into Early (prior to 1000 BC), Middle (1000–400 BC), and Late (400 BC – 250 AD). Major archaeological sites of this period include Nakbe, Uaxactun, Seibal, San Bartolo, Cival, and El Mirador. Maya society underwent a series of profound transformations between c. 100 AD and 250 AD, which resulted in the cessation of monumental building at many Preclassic cities and the inferred collapse of their political and economic systems, often characterized as the "Preclassic Collapse." History Early Preclassic (2000 BC–1000 BC) The roots of Maya civilization remain obscure, although broad parameters are increasingly well known. Paleo-environmental data indicate the presence of agriculturalists in the Maya lowlands by c. 3000 BC, although permanent agricultural settlements seem to have developed only gradually. Analysis of bones from early Maya grave sites indicate that, although maize had already become a major component of the diet (under 30% at Ceullo, Belize) by this time, fish, meat from game animals, and other hunted or gathered foods still made up a major component of the diet. Along with the gradual development of agriculture, basic forms of pottery began to appear, with simple designs and some slipped vessels. Around this time, the Olmec culture began to emerge in nearby Tabasco, granting the early Maya an important trading partner and beginning a period of prolonged contact that would have profound effects on Maya society. Middle Preclassic (1000 BC–400 BC) By around the year 1000 BC, the Maya city of Aguada Fénix was built in Tabasco, this archaeological site corresponds to a time of great change for Maya society. Since before its construction, the Mayas were nomads and did not use ceramics. They lived from hunting, fishing, and growing corn. However, from the construction of Aguada Fénix, it is shown that they began to use ceramics and became sedentary. Aguada Fénix marks the beginning of the construction of the Maya city-states that would flourish years later. The centuries of agricultural village life had begun to form the beginnings of a complex society: Prestige goods such as obsidian mirrors and jade mosaics began to appear, increasing the demand for more extensive trade. Canals and irrigation schemes demanding coordinated human effort began to appear with increasing complexity and scale. Gradually, villages began