Conclusion

The second millennium BCE was an era of migrations, warfare, and territorial state building in Afro-Eurasia. Whereas river-basin societies had flourished in the fourth and third millennia BCE in Mesopotamia, Egypt, the Indus Valley, and East Asia, now droughts shook the agrarian foundations of their economies. Old states crumbled; from the steppes and plateaus pastoral nomads and transhumant herders descended in search of food, grazing lands, and other opportunities. As transhumant herders pressed into the river-basin societies, the social and political fabric of these communities changed. Likewise, horse-riding nomads from steppe communities in Inner Eurasia conquered and settled in the agrarian states, bringing key innovations. Foremost were the horse chariots, which became a military catalyst sparking the evolution from smaller states to larger territorial states encompassing crowded cities, vast hinterlands, and broadened trade networks. The nomads and herders also adopted many of the settled peoples’ beliefs and customs. On land and sea, migrating peoples created zones of long-distance trade that linked agrarian societies.

Through a range of trade, migrations, and conquest throughout the second millennium BCE, the Nile Delta, the basin of the Tigris and Euphrates Rivers, the Indus Valley, and the Yellow River basin were brought into even closer contact than before. In Southwest Asia and the Nile River basin, the interaction led to an elaborate system of diplomatic relations. The first territorial states appeared in this millennium, composed of multiple communities living under common laws and customs. An alliance of farmers and warriors united agrarian production with political power to create and defend territorial boundaries. The new arrangements overshadowed the nomads’ historic role as predators and enabled them to become military elites within these new states. Through taxes and drafted labor, villagers repaid their rulers for local security and state-run diplomacy.

The rhythms of state formation differed where regimes were not closely packed together. In East Asia, for example, the absence of strong rivals allowed the emerging Shang dynasty to develop more gradually. Where landscapes had sharper divisions—as in the island archipelagos of the South Pacific and in the Mediterranean—small-scale, decentralized, and fragmented microsocieties emerged. But fragmentation is not the same as isolation. Even peoples in the worlds apart from the developments across Afro-Eurasia were not entirely secluded from the increasing flows of technologies, languages, goods, and migrants.