The first ancestral civilization in Mexico was that of the Olmecs (1200-600 B.C.), in the south of the modern day country. By 300 B.C., they were joined by the Zapotecs of Oaxaca, and by A.D. 250, the Maya were building temple pyramids in the Yucatan Peninsula. Central Mexico's great civilization flourished at Teotihuacan between A.D. 250 and A.D. 600, to be followed by the Toltecs at Xochicalco and Tula. The Aztecs were successors to this string of empires, settling at Tenochtitlan in the early 14th century. Almost 3,000 years of civilization was shattered in just two short years, following the landing of Hernan Cortes in 1519. The Aztecs were initially accommodating because, according to their calendar, the year 1519 promised the god Quetzalcoatl's return. By August 1521, Aztec resistance had ended. The Spanish-born were considered nobility. By the 18th century, criollos (people born of Spanish parents in New Spain) were seeking political power. In 1808, when Napoleon Bonaparte occupied Spain, direct Spanish control over New Spain suddenly ceased, and on September 1810, Miguel Hidalgo y Costilla, a criollo parish priest, issued his call to rebellion. Spain agreed to Mexican independence in 1821. In 1845, the Mexican- American War, under the Treaty of Guadalupe Hidalgo (1848), ceded a vast territory to the U.S. By 1862, France decided to colonize Mexico, which sparked yet another war, and in 1864, Archduke Maximilian of Habsburg became emperor of Mexico. His reign was bloodily ended by forces loyal to the country's former president, Benito Juarez. With the slogan "Order and Progress," dictator Porfirio Diaz, who ruled from 1878 to 1911, avoided war and piloted Mexico into the industrial age. During the Mexican Revolution (1910-1921), the basic ideological rift was between liberal reformers and radical leaders, such as Emiliano Zapata. Precursors of today's PRI (Institutional Revolutionary Party) took power in 1934. The oil boom of the late 1970s increased Mexico's oil revenues, but the oil surplus in the 1980s caused Mexico's worst recession in decades. In 1998, President Carlos Salinas de Gortari (PRI) was able to control inflation and establish a privatization program. The high point of Salinas' economic reform came with the North American Free Trade Agreement (NAFTA) on January 1, 1994. On the same day, the Ejercito Zapatista de Liberacion Nacional (EZLN) demanded improved social and economic justice. In March 1994, Luis Donaldo Colosio, Salinas' successor, was assassinated. His replacement, Ernesto Zedillo, was elected with 50 percent of the vote. Within days, Mexico's currency collapsed, bringing an economic recession. Zedillo's policies gradually pulled Mexico out of its economic woes. In the freest election since the Mexican Revolution, National Action Party (PAN) presidential candidate Vicente Fox won the election in 2000 and ended the PRI's 71-year reign. Fox sought to establish Mexico as an economic world player. In 2006, PAN candidate Felipe Calderon narrowly defeated the PRD's (Party of Democratic Revolution) Andres Lopez Obrador for the presidency. Since taking over, President Calderon has supported law and order, the free market system, and more opportunities for Mexico's poor. The next presidential elections will be held in 2012 and it appears that PRI may replace PAN due to economic and crime related frustrations."