Greenwich stood on the border between New Netherland and New England, a border which shifted at least three times in the Dutch Colonial period.
An Indian Deed in 1640 allowed Governor Theophilus Eaton of the New Haven Colony to 'purchase' the land from the Siwanoy Indians in exchange for 25 English coats.
In 1649 Petrus Stuyvesant signed a deed the included part of Greenwich in the Dutch settlement https://encyclopedia.nahc-mapping.org/document/indian-deed-land-east-bank-north-river.
Hidden History of Colonial Greenwich by Missy Wolfe
The Great Ledger - Records of the Town of Greenwich 1640-1742 Vols. I & II.