The colonists initially depended on the Native Americans for survival in the New World, and the Native Americans rapidly began to trade their foodstuffs, furs and wampum for the copper kettles, arms and metal tools of the colonists. Puritan settlers arrived in large numbers from 1620–1640, the 'Great Migration' that increased their need to acquire more land. Since the colonists had conflicting colonial and royal grants, the settlers depended on having Indian names on land deeds to mark legitimacy. This backfired, as John Wampas deeded off many lands to the colonists to curry favour, many of which were not even his.