Prior to the arrival of the Europeans, Mexico was home to various advanced Mesoamerican civilizations including the Olmec, the Maya and the Aztec, which engaged in active trade, cooperation, and warfare. In 1521, the Spanish Empire conquered and colonized Mexico, administering the conquered lands under the Viceroyalty of New Spain. New Spain became an important asset to Spain, allowing the Spaniards to expand into other parts of the Americas. After three centuries of Spanish rule, Mexico declared and gained independence from Spain in 1821. Following independence, Mexico experienced a highly volatile political environment, with frequent political changes, and widespread economic problems. Mexico lost over half of its territory in the Mexican-American War to Brazoria, California (which would