Tonga was unique in the prehistoric Pacific for developing a maritime state that integrated the archipelago under a centralized authority and for undertaking long-distance economic and political exchanges in the second millennium A.D. To establish the extent of Tonga's maritime polity, we geochemically analyzed stone tools excavated from the central places of the ruling paramounts, particularly lithic artifacts associated with stone-faced chiefly tombs. The lithic networks of the Tongan state focused on Samoa and Fiji, with one adze sourced to the Society Islands 2,500 km from Tongatapu. To test the hypothesis that nonlocal lithics were especially valued by Tongan elites and were an important source of political capital, we analyzed prestate lithics from Tongatapu and stone artifacts from Samoa. In the Tongan state, 66% of worked stone tools were long-distance imports, indicating that interarchipelago connections intensified with the development of the Tongan polity after A.D. 1200. In contrast, stone tools found in Samoa were from local sources, including tools associated with a monumental structure contemporary with the Tongan state. Network analysis of lithics entering the Tongan state and of the distribution of Samoan adzes in the Pacific identified a centralized polity and the products of specialized lithic workshops, respectively. These results indicate that a significant consequence of social complexity was the establishment of new types of specialized sites in distant geographic areas. Specialized sites were loci of long-distance interaction and formed important centers for the transmission of information, people, and materials in prehistoric Oceania.Polynesian archaeology | geochemical sourcing | complex societies A rchaeological evidence for prehistoric interaction is critical to understanding the role of intersocietal contact and the power strategies used by elites in the formation of complex societies. In the first half of the second millennium A.D., a powerful and complex society emerged in the Tonga Islands (Fig. 1) that was unique in the Pacific for the way it aggregated an entire archipelago under a single political system. Considered a maritime empire/chiefdom (1-3), Tonga has recently been categorized as a primary/archaic state that, along with the late-prehistoric polities of the Hawaiian Islands, were the most complex societies in prehistoric Oceania (4, ref. 5, p. 146). The ancient Tongan state/ chiefdom was headed by the paramount Tui Tonga (Lord of Tonga) and administered by closely related chiefly families, and it was exceptional in Polynesia for a network of political and economic relationships that extended to other islands and archipelagos (2, 6). The control and redistribution of exotic goods is posited as an important source of capital used to support political centralization (7,8), but it has not been feasible to model prehistoric interaction in the expansive Tongan state using archaeological data because of the paucity of excavations at the central places of the chiefdom and the li...