Adena cultures.

The social organization of native cultures became more complex in eastern North America during the Woodlands era (1500 B.C. to A.D. 700). The climate of the eastern portion of the continent was mild, moist, and lush and capable of supporting communities with large populations. The Woodlands peoples lived in temporary settlements near rivers and tributaries in groups of 25 to 150 people. Most of the Woodlands Indians continued to pursue the same lifestyle and maintained the same informal political structure as their ancestors had done during the Archaic period. However, in one area of eastern North America, Indians developed a distinctive way of life called the Adena culture. The Adena peoples emerged about 500 B.C. and were concentrated in the upper Ohio River valley. While the Adena societies had begun to cultivate a few plants, they primarily continued to obtain the...