The ancient Aztec Civilization
Ancient Aztec civilization was thriving in the early 1500s. It was located in present day Valley of Mexico, and largely based on Lake Texcoco. They had an extremely precise form of government, running water system, and their way of life was structured. The Aztec civilization is undeniably one of the most advanced civilizations to have ever existed. They have the most complete (and accurate) calendar to date; they had a very specific form of government and society. The Aztec civilization had thrived since around the 1200s, according to most historians, in the way in which the Spanish found them. Their civilization was strongly based on their monotheist beliefs, but also focused on the Aztec people themselves. They had a bartering system versus actual currency; they had great open air markets where you could trade everything from fish to feathers to pots and jewelry. The civilization ruled modern day Mexico, with nomads travelling far and wide the great city of Tenochititlan and Teotihuacan to live in the only modern cities of those times.
The demise and ultimate collapse of the great Aztec civilization came in 1521 when the Spanish crossed the Atlantic Ocean. Just like the Europeans that invaded the Unites States as we know it, the Spaniards went in search of gold, other treasures, and land to acquire for the king and queen of Spain. The Aztec collapse was a hard one, as the Spaniards brought disease with them that killed a lot of the Aztecs. They also brought their ideals and customs of the Catholic Church, and tried to convert all of the Aztecs into Christians, greatly going against their monotheist ways. They killed those that didn't comply or conform and many battles were fought before the final fall of the great Aztec empire.