By 1400 AD, almost all the Anasazi from throughout the Southwest had joined up into large pueblos scattered along the river systems of the Little Colorado and Rio Grande rivers in Arizona and New Mexico. Their descendants are still there in the few surviving pueblos. Why did they leave? It is impossible to find a single cause that can explain it, but there appear to be several that contributed. First, the climate in this period was somewhat unstable with erratic rainfall and periods of drought. This weather problem climaxed with a 38-year drought starting about 1270 that coincided with a world-wide cooling trend which significantly shortened the growing season. Perhaps also, the expanding population had pressed the limits of the land's capacity to support the people so that they were unable to survive the climatic upheavals of the 13th century.

Around 1100 AD, the city of Cahokia, 5 sq. km in area and home to 20,000- 40,000 people, was the largest settlement north of Mexico. It was located 12 kilometres east of the modern city of St. Louis in the United States, near where the Missouri and Mississippi rivers join up. Ruins today consist of 120 earth mounds where civic buildings and the homes of the nobles were located. The city centre, called the sacred precinct, was protected by a log stockade three to four metres high. Here the rulers of Cahokia lived and were buried. At the very centre was a huge earth mound, topped by a pole-framed temple more than 30 metres long. Merchants from Cahokia used the Mississippi and Missouri river systems to trade with people from the Gulf of Mexico to the Great Lakes to the Atlantic coast. After 1200 AD, the city went into decline for as yet unknown reasons, and by 1400 was virtually empty. Perhaps the people of Cahokia suffered from the same climatic changes as the Anasazi farther to the west.

Another example of sophisticated hunting technique of the hunter-gatherer nations of the Great Plains of North America is shown by Head-Smashed-In Buffalo Jump, in Alberta, Canada. This is one of the oldest and best preserved buffalo jumps, in use from about 4000 BC up to 1800 AD. Bison are not stupid, and just like most people, they don't jump off cliffs for no reason. At Head- Smashed-In, there is a kind of optical illusion. Although 10 metres high, the grassy cliff edge blends into fields beyond, and from a distance, there does not appear to be a drop at all.

When the herd of bison was located, your band would pack up camp, moving to the temporary camp closer to the buffalo. The people walked there on foot, using dogs to help them on their way. Upon arriving you set up camp, putting up tipis and racks to dry meat. Imitating a lost calf, a buffalo runner would try and trick the herd into following the pitiful bleating. As the buffalo neared the cliff, all the other hunters would sneak up behind the herd and scare the animals. Suddenly the older cows who usually lead the herd, as they get close enough, see the cliff edge, but with several hundred stampeding bison behind there is no chance to stop and turn, and soon dozens of animals are tumbling over the cliff. Later after the meat was prepared and everything was ready, there were great feasts. Food was not a worry again, at least for a little while.

Ruins