The United Mexican States (Spanish: Estados Unidos Mexicanos), often known simply as Mexico (Spanish: México) is a country located in North America, bordered at the north by the United States, and at the south by Guatemala and Belize in Central America. It is the northernmost and westernmost country in Latin America, and also the most populous Spanish-speaking country in the world.The official name is Estados Unidos Mexicanos, which translates as the United Mexican States. The term State of Mexico (Estado de México) does not refer to the country, but only to one state within Mexico, located near the center of the country adjacent to the Federal District.Mexico is divided into 31 states (estados) and a federal district. Each state has its own constitution and its citizens elect a governor as well as representatives to their respective state congresses.Situated in the southwestern part of mainland North America and roughly triangular in shape, Mexico stretches more than 3,000 kilometres (1,875 mi) from northwest to southeast. Its width is varied, from more than 2,000 kilometres (1,250 mi) in the north and less than 220 kilometres (137 mi) at the Isthmus of Tehuantepec in the south.The terrain and climate vary from rocky deserts in the north to tropical rain forest in the south. Mexico's major rivers include the Río Bravo del Norte (Rio Grande) on the northern border and the Usumacinta on its southern borders, respectively, together with the Grijalva, Balsas, Pánuco, and Yaqui in the interior. The Tropic of Cancer effectively divides the country into temperate and tropical zones. Land north of the twenty-fourth parallel experiences cooler temperatures during the winter months. South of the point, temperatures are fairly constant year round and vary solely as a function of elevation.

With an estimated 2005 population of about 106.5 million, Mexico is the most populous Spanish-speaking country in the world.Mexico is a racially and ethnically diverse country. Its three main ethnic groups are mestizos (mixed European and Amerindian), Amerindians, and Europeans. According to the CIA World Factbook, mestizos account for 60%, Amerindians for 30%, whites for 9%, and others 1%. [4] Whites are mostly Spanish descendants, though there are those descended from past or recent immigration of Germans, Italians, French, Portuguese, British, Swedish, Irish, and also white Americans. The "others" is largely comprised of Afro-Mexicans, Middle Easterner, and East Asian.
Mexico is also home for many other Latin American emigrants, including most numerously Argentines — Mexico being home to the largest Argentine population outside of Argentina [5] — Cubans, Brazilians, and other South and Central Americans. The PRI governments in power for most of the 20th century had a policy of granting asylum to fellow Latin Americans fleeing political persecution in their home countries.
Between 1800 and 300 BC, complex cultures began to form. Many matured into advanced Pre-Columbian Mesoamerican civilizations such as the: Olmec, Izapa, Teotihuacan, Maya, Zapotec, Mixtec, Huaxtec, Purepecha,Toltec and Mexica (Aztecs), which flourished for nearly 4,000 years before first contact with Europeans.
These indigenous civilizations are credited with many inventions in: building pyramid-temples, mathematics, astronomy, medicine, writing, highly-accurate calendars, fine arts, intensive agriculture, engineering, an abacus calculator (Nepohualtzitzin), a complex theology, and the wheel. Without any draft animals to do labor, however, the wheel had limited applications and was primarily used for art and toys. Metallurgy focused on copper, gold, and silver.Archaic inscriptions on rocks and rock walls all over northern Mexico (especially in the state of Nuevo León) demonstrate an early propensity for counting in Mexico. These very early and ancient count-markings were associated with astronomical events and underscore the influence that astronomical activities had upon Mexican natives, even before they possessed urbanization.In fact, many of the later Mexican based civilizations would all carefully build their cities and ceremonial centers according to specific astronomical events. Astronomy and the notion of human observation of celestial events would become central factors in the development of religious systems, writing systems, fine arts, and architecture. Pre-historic Mexican astronomers set in motion a tradition of obsessive observing, recording, and commemorating astronomical events that later become a hallmark of Mexican civilized achievements. Cities would be founded and built on astronomical principles, leaders would be appointed on celestial events, wars would be fought according to solar-calendars, and a complex theology using astronomical metaphors would organize the daily lives of millions of people.
While many city-states, kingdoms, and empires competed with one another for power and prestige, Mexico can be said to have had five major civilizations: The Olmec, Teotihuacan, the Toltec, the Mexica (a.k.a. Aztecs) and the Maya. These civilizations (with the exception of the politically-fragmented Maya) extended their reach across Mexico, and beyond, like no others. They consolidated power and distributed influence in matters of trade, art, politics, technology, and theology. Other regional power players made economic and political alliances with these five civilizations over the span of nearly 4,000 years. Many made war with them. But almost all found themselves within these five spheres of influence.
In 1519, the native civilizations of Mexico were invaded by Spanish troops numbering about a mere 600 soldiers, who brought with them superior weaponry and other things not known in America at that time, like horses, basic objects like the wheel (without which the native civilizations had -against all odds- managed to build empires) and old world diseases which were not present in America whose effects in terms of native mortality were certainly important. The Spanish also took advantage of a widespread resentment of brutal Aztec rule, making allies of peoples who were dominated by the Aztecs. This tactic allowed them a conquest which otherwise would have been impossible with their small numbers. Two years later in 1521, the Aztec capital of Tenochtitlan (Mexico City) was conquered. It is said that the dead from smallpox filled the streets and canals. Hundreds of thousands of Aztecs died of disease. Francisco Hernández de Córdoba explored the shores of southern Mexico in 1517, followed by Juan de Grijalva in 1518. The most important of the early Conquistadores was Hernán Cortés, who entered the country in 1519 from a native coastal town which he renamed "Puerto de la Villa Rica de la Vera Cruz" (present day Veracruz).Contrary to popular opinion, Spain did not conquer all of Mexico when Cortés conquered Tenochtitlan in 1521. It would take another two centuries after the Siege of Tenochtitlan before the Conquest of Mexico would be complete, as sporadic and ineffective rebellions, attacks, and wars continued against the Spanish by other native people. Disease ran rampant throughout Mexico, dropping the population from about eight million to two million by 1600.