Estados Unidos Mexicanos is one of 18 Megadiverse countries. With over 200,000 different animal species, it is home to 10-12% of the world's biodiversity.
The area was home to complex civilizations including the Maya, Olmec, Zapotec, and Aztec. At its peak (c. 150-450 CE) the city of Teotihuacan was probably the largest on earth. These civilizations flourished for nearly 4,000 years.
In the early 16th century, the Spanish conquest wiped out millions of people due mainly to smallpox. After a struggle, independence was regained in 1821. The Mexican-American War of 1846-1848 resulted in Mexico giving up almost half its land -- including California and New Mexico -- to the United States.