The Unkechaug people lived in the part of Long Island that now includes Town of Brookhaven. The Unkechaugi are descendants of the Quiripi-speaking Native Americans, who occupied much of southern New England and central Long Island at the time of European encounter in the colonial era. Historically they spoke an Algonquian language.
"Sicktawach," which could be either the Carmans River or the Connetguot River in Suffolk County, Long Island, was part of their territory, and played a key role in the wreck of the Prince Maurice in March of 1657.
Please see the map here, and be sure to adjust the layers to show tribal areas: https://nahc-mapping.org/mappingNY/#11.21/40.7933/-72.8269
Further reading is available here:
https://en.wikipedia.org/wiki/Poospatuck_Reservation
https://nativelongisland.com/listing/unkechaug-indian-reservation/