Scholars and the public alike view the European arrival in the Western Hemisphere as heralding a decisive break between millennia of continual, but typically gradual, changes in native societies and tumultuous centuries of societal and population collapse. Much is true about a characterization of the postcontact period as a time when native populations underwent calamitous declines, well-established cultural patterns were disrupted, and people were displaced from long-occupied land. But in eastern North America, such statements, baldly stated, seriously mischaracterize the dynamic nature of precontact societies and how centuries-long histories of regional population growth and decline, societal change, and intergroup relations set the stage for what took place following contact. Archaeological data show that during the last several centuries of the precontact period there was considerable variation across eastern North America in how societies were structured and, the particular focus of this chapter, both the distribution of people and the intensity of conflict among them. The identification of a marked precontact reduction in the midcontinent’s inhabitants and a band of conflict-prone societies bordering the depopulated area shows that the situation immediately prior to ca. AD 1500 had a greater influence on what took place afterwards than has been previously recognized.