The Mangarevan language of the Gambier Islands, situated between Tahiti and Easter Island, displays one of the largest collections of doublets among the fortyodd Polynesian languages. These doublets indicate a pre-Proto-Central Eastern settlement of the island from the Marquesas via the Eastern Tuamotus. They also witness a later Proto-Central Eastern intrusion on the island of similar provenience. The cumulative weight of evidence suggests that Proto-Southeastern Polynesian, a hitherto unrecognized language that seemingly comprised ProtoEastern Polynesian's first differentiation, was spoken by the first settlers of the Eastern Tuamotus, Mangareva, Pitcairn, Henderson, and Rapanui.