Gagil in the context of Chuuk Lagoon

Yap State is one of the four states of the Federated States of Micronesia, located in the westernmost portion of the country. The state borders Palau to the southwest, Guam to the north, and Chuuk State to the east. According to the state's population census carried out in 2020, the total population is 11,577 residing across a total area of 119.54 sq km (46.15 sq mi), though a large majority of the area is water. The only town area in the state, Colonia, serves as the state capital.

What is now current-day Yap State and some parts of Chuuk State were the historical Yapese Empire, which at its peak, controlled 1,300 km of the western Pacific comprising all the inhabited islands and atolls between Yap and Chuuk. The rulers of the chiefdom of Gagil in Yap maintained sovereignty of these islands to the east and extracted resources and tribute, maintaining close economic and political relationships with the different island groups. After losing its influence and becoming incorporated territories of Spain, the German Empire, the Japanese Empire, and the United States through the UN-mandated Trust Territory of the Pacific Islands (TTPI), Yap and the islands and atolls between Yap and Chuuk formed Yap State upon the founding of the FSM.

The Yapese Empire was an ancient maritime empire located in the western Caroline Islands in the north Pacific region of Micronesia since around the 9th century, AD. In circa 950 AD, Yap became the seat of the empire when Gatcheper village in the chiefdom of Gagil (modern-day Gagil Municipality) established an expansive maritime trade network and exerted socioeconomic and political influence to its neighboring islands to the east. Although small and informal compared to other marine empires, the empire at its peak covered over 1,300 kilometers, stretching from the Yap main islands to parts of modern-day Chuuk State. The empire coexisted with the Tongan Empire located in the southern Pacific.