Brief History
The Aztec was a tribe of Indians that wandered into the Valley of Mexico in 1300CE. The Aztecs had to adapt to the swampy shores of Lake Texcoco, due to the fact that other tribes took fertile lands and were already in residence. The Aztecs build canoes to fish and hunt birds that lived near the water, created more land for agriculture, dikes to hold back the water and floating gardens to grow food. After the settled in, they conquered neighbouring tribes and build an empire.
In around 1500CE the Spanish conquered the Aztecs. The Spanish arrived with guns, huge fighting dogs, horses and disease; although the Aztecs were amazing warrior they could not fight against disease, many died. The Spanish received help from other tribes to conquer the Aztecs as the other tribes wanted revenge. These tribes did not expect to be conquered themselves.
By the mid-1500's the Aztec Empire had collapassed and the Spanish has taken over the whole region.
Source: http://aztecs.mrdonn.org/quick-history.html