Pueblo people (sometimes called the Anasazi) began to build mud-brick houses for themselves in the south-west part of North America (modern Colorado, northern Arizona, and New Mexico) about 100 BC, during the Middle Woodland period (the time of the Han dynasty in China, and the Roman republic). At this point archaeologists call them the Basket Maker people.
Basket Maker people built houses of wooden poles and mud-brick, often dug into pits in the ground, or they lived in caves which were easy to find among the sandstone cliffs. People hunted and gathered most of their food, but by 1 AD they also grew pumpkins and corn, which they had learned about from Maya people to their south. They did not use pottery (even though Maya people did), but mainly baskets.
Around 500 or 600 AD, people also learned how to grow beans and domesticated turkeys (or maybe got domesticated turkeys from Maya people), and then it became easier to get their food from farming and herding turkeys than from hunting and gathering. So people mostly became farmers. Now that they were settled down, they began to make pottery to keep their stuff in instead of baskets.
By 700 AD these people began to build big apartment houses out of mud-brick and sometimes out of stone. People's houses became much bigger than they had been before. They built their houses up on top of high cliffs called mesas. They called these houses pueblos, and they called the mud-brick adobe. People also began to grow cotton for clothing, and their pottery got more complicated and had more different shapes like jugs, jars, plates, bowls, and cups. Pueblo people got rich and powerful, and spread out to take over more land as far north as central Utah and southern Colorado, and as far south as a good part of Mexico. They were trading their turquoise for pretty parrot feathers and other things which came from as far away as the Maya in Central America.
The South-west is very dry, and so people needed to be careful to get every last bit of water they could find. They learned to build systems of dams and stone cisterns to store water from melting snow up in the mountains. This was not just for drinking water, but also they needed water to irrigate their corn and beans and pumpkins so they would grow.
Around 1200 AD, Pueblo people stopped living on top of the mesas and they moved to pueblos (houses) that were built half-way up the cliffs, in caves. Nobody knows why they decided to move to these caves. Maybe the weather got too hot and it was cooler in the caves. Maybe they were fighting wars and they needed to be in a safer place. But some people also moved back to the mesa tops - some people think this was safer than the cliffs. It's possible that Ute and Shoshone people invaded at this time.
But around 1300 AD, Pueblo people stopped building houses altogether and moved away from their homes. Probably they moved because a global warming trend meant that the weather became too dry, and people couldn't farm corn and beans there anymore. They lost all their power, and they stopped living in their fine houses, and they stopped farming. They traveled south-west, into southern Arizona and New Mexico, looking for new homes. That's when the Pueblo people first met the Navajo, who were moving south into Arizona and New Mexico about the same time.
To find out more about Pueblo history, check out these books from Amazon.com or from your library:
by Alice Flanagan (1998). A good choice for younger kids.
Mother Earth, Father Sky: Pueblo Indians of the American Southwest, by David Lavender (1998). Good for middle school, with a lot on the Anasazi and then a little about the Pueblos near the end.
The Pueblo: Farmers of the Southwest, by Jane Duden (2000). Good for middle school, with first history and then a substantial section about Pueblo people today.