Anasazi means "ancient enemies" or "enemies of our ancestors" in Navajo (some say that it is ancient ones). Though their population was greatest between 700 and 1350 CE, estimates indicate that they lived in the four-corners area for nearly two thousand years. It is unclear where exactly they came from, and who they are descended from. In fact, as v3rgez mentions, almost nothing is known about the Anasazi people. What little we do know comes from the ruins that they left scattered about the Southwestern United States at places such as Chaco Canyon and Mesa Verde National Park. Most of what is known about them is purely theoretical, but there is good evidence for each theory. Most of the knowledge that we have is actually based off of what has been found in the excavated remains of garbage heaps that they left behind. These contain a wide variety of pottery, as well as many types of jewelry and baskets. Modern knowledge of the Anasazi is based almost entirely on these garbage piles. The dates that are associated with all of the major Anasazi events are based on dendrochronology, the study of tree rings to determine age.
Analysis of skeletons has revealed that the Anasazi were fairly short, growing to be only about 5'2" tall. They had no written language, except for a few petroglyphs. Not much is known about their day to day lifestyle, although many have speculated. We do know that they were able to weave intricate baskets and that later they learned to make pottery, based on artifacts that have been found. Their pots and baskets both had intricate patterns on them, many of which can be seen in very good condition in the museums. Unfortunately, wholesale looting of many of the larger ruins has left tragically few well preserved specimens. They created ropes by weaving together fibers from the Yucca Plant. In some of the better protected ruins, there is still plaster with red-painted patterns remaining on the walls. All of these things indicate that the Anasazi advanced technologically during their stay, although not to the level of many other groups of pre-Columbian Americans.
The Anasazi were primarily an agricultural people whose farms were located on top of the mesas that surrounded their homes. They gathered berries and pinion nuts, both of which were fairly plentiful in the area. As time wore on, they also began to hunt some small game, but they still relied most heavily on agricultural products. Trading was another component of the subsistence of the Anasazi. We know that they traded through extensive networks throughout the west, because many artifacts found contain sea shells, which clearly weren't indigenous. Because the southwest is a desert, water was a scarce
resource. But obviously, any group that bases its livelihood on farming requires water. Though some drinking water was available in small streams at the bottoms of canyons, this water was difficult to get to. Instead, the Anasazi placed pots at the back of caves, where pure water would seep through the pourous rocks of the cliffs. If you visit Mesa Verde National Park, Hovenweep National
Monument, Canyon de Chelly National Monument, or any of the other major ruin sites, you can see many examples.
Contrary to popular belief, the Anasazi weren't primarily cliff dwellers that comprise the most famous Anasazi ruins. In fact, many archaeologists believe that they only lived in these cliff dwellings for about 100 years of the time that they lived in the area. As with most things related to the Anasazi people, the reasons for this are a mystery. Some believe that it was to protect themselves from neighboring tribes or predatory animals, and others believe it was simply to escape the heat. But, the cliff dwellings certainly represent the apex of the Anasazi's technical achievement.
In any event, the Anasazi disappeared abrubtly and completely around 1350. Traditionally, the reason offered for this is a severe drought that must have killed either the crops or most of the people. Studies of tree rings indicate that the time was one of severe drought. But, within the past ten years or so, many people have begun to speculate that perhaps something else caused the migration, because the drought simply wouldn't have been enough. Some have suggested war, either within the tribe, or with a neighboring tribes. But, it would seem that the Anasazi were too numerous (possibly as many as 20,000) to
have been defeated so quickly. Plus, whoever would have won such a war didn't stay around afterwards, which doesn't seem to make sense. Other believe that some sort of ideological change caused a mass migration. Usually, this is presumed to be some sort of religious idea that drew the Anasazi away from the four corners. The evidence for this is that none of the descendent cultures of the Anasazi seem to have no religious structures or rituals similar to those of the Anasazi. Whereas Anasazi ruins contain kivas, either above ground such as at Hovenweep or below ground, like those at Mesa Verde, the villages of their descendents contain no such structures. No trace of a distinct culture like the Anasazi exists after this time. Most scholars agree that the Anasazi probably migrated to various places, and were the ancestors to the Hopi indians, a Kachina pueblo tribe. Perhaps Kachina was the religion that brought the Anasazi away.
The Hopi oral tradition tells the story differently. They believe that they came from the center of the earth, and that they emerged near the meeting point of the Colorado River and the Little Colorado River. They were instructed by a spirit to travel in all directions, and then return. Some are said to have made it as far as the jungles of central and South America before the faithful returned to the desert. In any case, the modern Hopi language shows little influence of southern indian languages.
Obviously, we will never know what exactly happened to the Anasazi, or even very much about their lives. But it's fun to speculate. And with the huge number of small, undiscovered ruins in the southwest, it is still possible that something will be found. But they are certainly an interesting culture. Anyone interested in learning more should definitely visit one of the many monuments in the four-corners area dedicated to the ruins.