What is "mattabesset"

Mattabesset was a region and settlement once occupied by Algonquian language-speaking Native Americans called the Wangunk, along the Connecticut River. The Mattabesset River reaches the Connecticut River near Middletown, Connecticut. The settlement of Mattabesset became Middletown, on the east bank of the Connecticut, and a succession of settlements on the west, including Chatham and Middle Haddam which today is East Hampton, Connecticut.