Short answers, pulled from the story.
The Caroline Islands are a scattered archipelago in the western Pacific Ocean, north of New Guinea. They extend across approximately 3,540 km, from the westernmost island, Tobi, in Palau, to the easternmost island, Kosrae, a state of the Federated States of Micronesia.
The first European contact came in 1525, when a storm carried the Portuguese navigators Diogo da Rocha and Gomes de Sequeira to several of the Caroline Islands. They stayed for several months, leaving on the 20th of January 1526. Spanish explorer Alvaro de Saavedra Cerón claimed the Ulithi Islands for Spain on the 1st of January 1528.
The inhabitants of Yap use large calcite or limestone discs, ranging from 6 inches to 12 feet in diameter and weighing up to nearly 5 tons, as a form of currency. The stones were quarried in the Pelew Islands, about 200 miles away. Ownership can transfer without the stone moving, based on shared community understanding.
Spanish explorer Francisco de Lezcano named the islands Las Carolinas in 1686, in honor of Charles II of Spain. The name was later extended to cover a broader area that British explorers would call the Gilbert Islands and the Marshall Islands.
After the Spanish-American War of 1898, Spain sold the Caroline Islands and the Northern Marianas to the German Empire under the German-Spanish Treaty of 1899 for 25 million pesetas. Japan occupied the islands in 1914 and received a League of Nations mandate over them in 1920. After World War II they became American trust territories.
Mau Piailug (1932-2010) was a Micronesian navigator from the Carolinian island of Satawal. He was trained in the traditional navigation techniques of the Weriyeng school. In the 1970s he shared his knowledge with the Polynesian Voyaging Society, helping revive traditional Pacific navigation practices.