Wikipedia
Metoac is a term erroneously used to describe Native Americans on Long Island in New York, in the belief that bands were distinct tribes of this location. Scholars now understand that these historic peoples were part of three major cultural groups: the Lenape, Wappinger- Wangunk- Quinnipiac and Pequot peoples, both part of the Algonquian languages family. The amateur anthropologist and U.S. Congressman Silas Wood published a book in the 19th century mistakenly claiming that several American Indian tribes were distinct to Long Island, New York. He collectively called them the Metoac.
Modern scientific scholarship has shown that Native American peoples on the island belonged to two major language and cultural groups among the Algonquian peoples who occupied Atlantic coastal areas from Canada through the American South. The bands in the western part of Long Island were related to those Algonquins which previously settled in the territory East of the Hudson river, related to peoples in what is now western Connecticut. Those to the east were more related culturally and linguistically to the Algonquian tribes of New England across Long Island Sound, such as the Pequot. Wood (and earlier colonial settlers) often confused Indian place names, by which the bands were known, as the names for different "tribes" living there.
Wood may have derived his collective term from metau-hok, the Algonquian word for the rough periwinkle, which played an important role in the economy of the region before and after the arrival of Europeans. Those entering western Long Island were mostly Dutch colonists, some from New Netherland. The eastern part of the island was colonized by English settlers from southern New England. Indigenous populations declined significantly within a few decades of European contact, due to diseases. Many of the place names given by the Lenape and Pequot populations are still in use today. The Shinnecock Indian Nation, based at what is now Southampton, New York in Suffolk County, has gained federal recognition as a tribe and has a reservation there.