It was the Metoac's grave misfortune to occupy the northern shore of Long Island which was the source of the best wampum (beads of shells strung in strands and used by American Indians as money) in the Northeast. Each summer, the Metoac harvested clam shells from the waters of Long Island Sound which, during the winter, were painstakingly fashioned into small beads. Strung together in long strands, they were called "wampompeag" – shortened somewhat by the English colonists into the more familiar form of "wampum" …the Dutch called it siwan (sewan). The Metoac traded this painstakingly crafted product to other tribes (most notably the Mahican) and prospered as a result. Passed from tribe to tribe, Long Island wampum made its way as far west as the Black Hills of South Dakota. The strings of shell beads were sometimes employed as a rudimentary currency in native trade, but it was also valued for personal decoration. Arranged into belts whose designs could convey ideas, wampum was also employed in native diplomacy to bind important agreements such as war and peace.