Pleistocene era

Glaciers that formed during the Pleistocene era altered the Earth's topography. Sea levels rose and fell, periodically exposing intercontinental land bridges. One land bridge, Beringia, linked Asia with North America. Scientific theories suggest that the first people in this continent crossed this land bridge from Asia over 12,000 years ago. There is evidence that indicates that people were in North America by 20,000 and perhaps 30,000 years ago.

Oral histories of Native American peoples do not refer to such migration: tribal histories place their origins on this continent. Some traditional accounts also describe creation of the Rocky Mountains and other landforms in this region.

Vast, shifting ice sheets covered much of northern North America during the Pleistocene era. Between the Laurentide and Cordilleron ice sheets, which blanketed most of the Northwest, a narrow corridor of land apparently remained ice-free, running along the eastern front of the Rocky Mountains from what is now northern Canada to Montana. People and the animals they hunted may have traveled on this open land with the forbidding glaciated terrain on either side.

Trade

Indian peoples in North America developed complex trading networks with links extending across the continent. Ideas, technologies, raw materials, manufactured items, and food were carried hundreds and thousands of miles in this manner. Trade between the tribes also brought groups from different regions together, allowing them to share information and ideas with one another.

This network enabled such materials as obsidian from the Yellowstone Plateau to circulate as far east as New York state about 1,700 years ago. Flint from the Dakotas and obsidians from Idaho and Wyoming have all been found at prehistoric sites in Montana.

From their own region, Montana's prehistoric peoples probably traded game meats, pemmican, and hides from the plains and mountains; salmon from the western rivers; sweetgrass from the prairies of eastern Montana; bitterroot and camas from the intermontane valleys; and red ochre and sheephorn from the mountains. In return, they received shell from the Pacific Coast and corn from farming tribes along the Missouri River to the east.

Weapons

Montana peoples used a variety of hunting weapons through the centuries. They designed sophisticated weapons that were efficient and deadly accurate. The earliest weapons were stone-tipped spears that hunters probably thrust or threw at their prey.

By the end of the Ice Age, a throwing device called the atlatl may have been in widespread use in North America. The atlatl was carved of wood and hooked into the end of darts and spears. It extended a hunter's reach, adding greater power and accuracy when he threw spears or darts and enabling him to bring down his pretty for a greater distance. A skillful atlatl hunter could hit a target 50 to 75 yards away.

About 1,500 years ago, peoples throughout North America adopted the bow and arrow. This lightweight, highly portably weapon allowed hunters and warriors freer movement and greater stealth. Bow makers fashioned bows from ash, osage orange, yew, and other native woods and strung them with sinew. Wooden arrows were tipped with stone points, which were often resharpened and reused when they broke.