After the Paleo-Indian period, beginning about 8000 BC, came the Archaic period. During the Early Archaic period, the Ice Age ended and the great glaciers that had covered the northern part of North America gradually melted away. Hunters began to use new types of spearpoints. Probably there were getting to be more and more people in North America, and they started to form bigger groups, perhaps with chiefs, and to trade with other groups to get better stone for their spear points. Many people lived along rivers, and used canoes to trade up and down the river. During this warmer time, new people came over from Siberia into North America by way of the Arctic Ocean. They gradually traveled all over the Arctic coast, and got to be known as the Tuniit people.
After 6000 BC, in the Middle Archaic period, there were enough people in North America that things began to get a little more crowded. People began to gather more of their food - more nuts, fruits, berries, and seeds like wild rice and sunflower seeds. They also settled down in houses with storage pits, though they didn't stay in their houses all year round. In the southern part of North America, the Middle Archaic ended about 3000 BC, but further north among the Chinook, people lived in a Middle Archaic way until about 1000 BC.
By 3000 BC, in the Late Archaic period, some people living along the Mississippi River (in modern Louisiana) may have been building earth burial mounds - this is the same time as the Pyramids in Egypt (but the Pyramids are built of cut stone). Some towns got to be bigger than others and probably controlled the villages around them, as in a complex chiefdom. People began to specialize what they hunted and gathered according to what was available where they were living. Along the middle of the East Coast, for instance, people gathered fresh-water mussels, while further south they lived on salt-water oysters. Near the end of the Archaic period, about 1500 BC, some Iroquois people seem to have split off and traveled south to become the Cherokee. At the same time, people even further south (in modern Florida) began to use pottery, and Pueblo people in the south-west of North America (modern Arizona) began to farm corn and beans that they had gotten from the pre-Olmec people in Mexico to their south. The Late Archaic period lasted until about 1000 BC.