Fort Nassau was a factorij in New Netherland between 1627-1651 located at the mouth of Big Timber Creek at its confluence with the Delaware River. It was the first known permanent European-built structure in what would become the state of New Jersey. The creek name is a derived from the Dutch language Timmer Kill as recorded by David Pietersen de Vries in his memoirs of his journey of 1630–1633. The Delaware Valley and its bay was called the "South River" (Dutch: Zuyd Rivier); the "North River" of the colony was the Hudson River. The factorij was established for the fur trade, mostly in beaver pelts, with the indigenous populations of Susquehannock, who spoke an Iroguoian language, and the Lenape, whose language was of the Algonquian family.