The sovereignty and governance of maritime territories by ancient Chinese dynastic states manifested primarily through territorial claims, navigation rights, administration of coastal populations, exploitation of marine resources, and management of coastal border crossings. The Qin and Han dynasties asserted territorial sovereignty over maritime domains by conducting sacrificial ceremonies to the Eastern and Southern Seas at Langya (琅邪), Donglai (东莱), Kuaiji (会稽), and other coastal sites, while consolidating control through military and political strategies. By dominating key coastal cities and ports, these dynasties secured stable navigation rights across the Bohai Sea, northern Yellow Sea, and nearshore waters of the Eastern and South China Seas. Furthermore, through the establishment of commanderies and counties, and the organization of townships and villages, they integrated coastal populations—including maritime communities—into the imperial household registration and taxes and corvée system. The appointment of Salt Officials and Water Officials enabled state control and monopolization over sea salt production and marine resource extraction (e.g., fisheries, pearls) in coastal zones. Additionally, the construction of frontier passes, watchtowers, and border fortifications (障塞) regulated crossborder movement, foreign relations, and trade via coastal land and sea routes. Exercising governance across a vast maritime frontier—extending from the Lelang Frontier (乐浪徼) in the northeast to the Rinan Barrier (日南障塞) in the southeast—the Qin and Han dynasties established the foundational framework for China’s historical maritime territoriality and its administrative systems.