How Were Native Americans Advanced?

In the Americas we faced a major problem with building major civilizations. The problem lied within the fact we had no beast of burden. The larger animals that inhabited the Americas died off during the mid-little ice age. The Americans eventually became a hunter-gather type people. The exception to the rule in North America would have been the Mound Builders. The (MB) were successful for a short period in time. The main crop for these people was maze; however, maze did not hold significant nutritional value. The (MB) as a society eventually converted to cannibalism, and other means of action that lead to the demise of their society. I believe the Apachee developed a written alphabet which was a breakthrough for the Indians in this period in time. The Incas, myas and aztecs are the real exception to the rule. Primarily in meso-america the myas built large temples and developed a scenes of irrigation for their crops. The myan people devoloped a calander system that predicted the star patterns, solar cycles and predicted revolutions through time. (not completely proven but one was found.) The myan and aztec people were said to have 13 crystal skulls. These skulls were divided amongst 13 elders. This was generations ahead of their time. The actual skull that was found is said to be flawless. It would have taken someone 13 life-times to complete this work with the tools avaliable. It was said that if the 13 unite it will tell us our past, present, and future. The myans were successful and were advanced in comparison. It is said that the demise of the Myas came with a drought. When there was no water shortly there was no people. The Aztecs built great temples as well. If we consider any particular people advanced in the Americas these were the people. The aztecs were the pinnical of the early American people. The advanced irrigation systems and a trading system these people had it good, for a while. When the Spanish came over they fought long and hard to destroy the aztecs. The aztecs were vicious people;However, the Spanish defeated the Aztecs. The empires were looted and the gold was taken back to Spain and used to fight a religious war.