México's first established culture, had alot of influence. Later groups are known to have borrowed heavily from the Olmecs. The Olmec culture is very mysterious, since we know almost nothing about where they came from, or why they disappeared.
This city state of Teotihuacán located on the central highland of México covered an area of about 22.5 sq. km. Its population reached about 200,000 inhabitants by the year 350 AD (probably the largest city in the world at that time). They were the most highly urbanized in the New World, its religious, political and economical influence covered almost all the Mesoamerican territory.
The Toltecs occupied the northern regions of the Valley of México. They built Tula, (one of México's most impressive ancient cities). They strongly influenced later in the Mayan and Aztec cultures.
They controlled a huge empire, created complex systems of mathematics and astrology,and they were also skills traders. They were master architects and engineers, and had a highly ornamented architecture. Of all the indigenous cultures, they are considered to have been the most influential.
The Aztecs are probably the most well-known of all México's ancient cultures. The Aztec empire was composed of three Nahua's groups established in the Valley of Mexico with Tenochtitlán (which is now Mexico City) as the main city-state. Their empire was huge when Spanish conquistadors arrived in 1519. By 1521 they were conquered by the troops of Hernán Cortés.