Many different tribes came and went from the shores of the lake without establishing a culture more important than other in the southeast of today's Mexico. It was not until the arrival of the Aztecs, a tribe of people coming from the west, when the area acquired its importance.
The Aztecs migrated following an ancient legend that prophesied that they would find the site for their new city in a place where they would see a mythical vision fulfilled: an eagle eating a snake while standing on a cactus. The Aztecs eventually came across this vision on what was then a small swampy island in Lake Texcoco. Not deterred by this, they invented a system to dry the land by setting up small plots in which they produced all the food they required. When enough land was dry they would begin to build there. Tenochtitlán (the Nahuatl language name for the city) was founded in 1325.
A thriving culture developed, and the Aztec empire came to dominate other tribes all around Mexico. The island was perpetually enlarged as Tenochtitlán grew to become the largest and most powerful city in Mesoamerica. Commercial routes were developed that brought goods from places as far as the Gulf of Mexico, the Pacific Ocean and perhaps even the Incan Empire.
The city was connected to the mainland by a series of wide causeways with bridges. The city was interlaced with a series of canals, so that all sections of the city could be visited either on foot or via canoe.
After a flood of Lake Texcoco, the city was rebuilt in a style that made it one of the grandest ever in Mesoamerica under Emperor Auitzotl.
Then Spanish conquistador Hernán Cortés arrived in Tenochtitlán on November 8, 1519 and Aztec ruler Moctezuma II, thinking him to be the returing god Quetzalcoatl, welcomed him with great pomp. Some of the conquistadores had traveled as widely as as Venice and Constantinople, and many said that Tenochtitlán was as large and fine a city as any they had seen.
Cortés and his men eventually conquered the city on August 13, 1521 after years of battle which destroyed much of the city. The rest of the city was either destroyed, dismantled or buried as Mexico City was built on top of it.
For the later history of this city, see: History of Mexico City