Wiktionary
n. 1 a state whose power derives from its naval or commercial supremacy on the seas 2 maritime supremacy
Wikipedia
A thalassocracy (from Greek language (thalassa), meaning "sea", and (kratein), meaning "to rule", giving (thalassokratia), "rule of the sea") is a state with primarily maritime realms—an empire at sea (such as the Phoenician network of merchant cities) or a sea-borne empire. Traditional thalassocracies seldom dominate interiors, even in their home territories (for example: Phoenician Tyre, Sidon and Carthage or Srivijaya and Majapahit in Southeast Asia). One can distinguish this traditional sense of thalassocracy from an "empire", where the state's territories, though possibly linked principally or solely by the sea lanes, generally extend into mainland interiors (for example: the Bruneian Empire (1368–1888) in Asia). Compare to - land-based hegemony.
The term thalassocracy can also simply refer to naval supremacy, in either military or commercial senses of the word supremacy. The Greeks first used the word thalassocracy to describe the government of the Minoan civilization, whose power depended on its navy. Herodotus also spoke of the need to counter the Phoenician thalassocracy by developing a Greek "empire of the sea".
Usage examples of "thalassocracy".
Ranthas and His servants, I surrender the countship of Lepidor to Admiral Karao as representative of the Thalassocracy of Cambress.