When you look at the Mayan Temples and cliff Dwellings and the incredible artifacts and ruins at Machu Picchu, you have to ask yourself a few questions. Number one in the case of the high altitude of the Machu Picchu deal and the Cliff Dwellings in the mountain away from all predators, etc. A fortress so to speak. You have to come away with the question why. What were they hiding from? Hostile members of their own species, other tribes. Some have talked about aliens. Others about wild animals, some about plagues. Having watched the weather for some time and realizing the incredible droughts and fires that exist in some of these places, caused generally from lightening. Perhaps some of this is weather related. Where did they go? Well perhaps they went to where the water was, since we know from looking at present times that water does not always flow in the areas of the cliff dwellings in NM and CO.http://www.nps.gov/cach/This whole area built up from 350 AD to about 1330 AD. Why did they leave? Some 50,000 sites in all times the number of people per area, which had to be a huge population of people. If you have a flourishing culture and all of a sudden in 1150 most all left. Some 100,000 sites are expected to be under the ground and around Four Corners. Were the Indians hiding from warring tribes in defense? Look at Keitsu (Sp?)in AZ, you cannot even get there and the place is literally in brand new condition still to this day. These people built this in 1270 approximately and then they too left. WHY? Attackers? I say it was drought, worse even than we are having throughout NM, CO, AZ, and Western NE, KA, OK, SD, ND and TX. And also in MT, WY. They needed food too; with that population they had to have a problem with growing and hunting food. They must have migrated. BY 1300s the entire civilization gone. Then of course the high plains of Indians in South America, who made pictures in the dirt. And for those who claim it could not be aliens, then why would a tribe, the Nausca move thousands of tons of dirt around where the weather gets above 120 degrees. Now they also used a canal system and a makeshift ditches, aqueducts and wells so they could farm.Many of the subterranean water supply had lines pointing towards them, could they be trying to alert the water gods as to where the water was at so they would let it rain and the Nausca could use it for agriculture? The lines being made with groves, forming line art and pictures which can be seen even in the upper atmosphere and a trained eye can see them from orbit if you know where to look. Some started in 100 BC when they were drawn and did it for 1000 years. But the Paracas did this too and they started 400 years before about 500 BC. Now mind you in times of 500 BC in Europe no such encounters were written about in the history of what we know, but it appears from the multiple gods of the day and most modernized cultures and societies of the time did participate in tributes to the gods of what we might call Mother Nature. Similar to the gods of wind and fire and water of the Native Indians of these various regions.In the US and I recommend a visit to Mesa Verde, Canyon de Chelly to see what I mean about the cliff dwellings and lightening, fires and water supply. As well as the great fortress like setting. These dwellings built out of sand stone are still very strong and magnificent and only a few have been covered by landslides. One can only imagine the empire of the Anastasa Indian Civilization. One of the exhibits called “the great house” some 400 rooms, Chaco center.Think about it 1 million lbs. of dirt were moved. Some 2500 trees used, without being dragged, perhaps from 80 miles away. There were actually roads leading into Chaco Canyon. All this in 850 AD. Let us look at other cultures such as in Afghanistan and the underground tunnels and aqueducts and rivers. These types of issues are global. A period of no water, supreme droughts, over taxed and depleted soil, over population for hunting the number of migratory and year round domestic animals. Lack of water, fires, and food and when territorial issues happen from lack of supplies, you have the strong surviving over the weak. The warriors take over and the civilization collapses.