The peoples of what is now Mexico and much of Central America, who formed organized societies as early as 10,000 BC. The first complex society in the Americas emerged in approximately 1,000 BC, while a more sophisticated culture came at around 800 AD. Meso-American groups included the Mayans and the Aztec, or as they called themselves, the Mexica. The Mayan civilization developed a written language, a numerical system, an accurate calendar, an advanced agricultural system, and important new international trade routes. The Mexica established a city called Tenochtitlan and soon became the dominant power of central Mexico, and beyond, through a system of tribute enforced by military force. These civilizations were for many centuries the center of civilized life in the Americas, and the trade and culture hub. They were brought down by the Europeans due to disease and disunity, but were impressive civilizations nonetheless.