Boston's early European settlers had first called the area Trimountaine (after its "three mountains"—only traces of which remain today) but later renamed it Boston after Boston, Lincolnshire, England, the origin of several prominent colonists. The renaming, on September 7, 1630 (Old Style),[b] was by Puritan colonists from England, who had moved over from Charlestown earlier that year in quest of fresh water. Their settlement was initially limited to the Shawmut Peninsula, at that time surrounded by the Massachusetts Bay and Charles River and connected to the mainland by a narrow isthmus. The peninsula is known to have been inhabited as early as 5000 BC.