In the month of November of the year 1620, the Mayflower reached the coast of Massachusetts, full of Puritan Separatists, those wanting to separate from the Church of England; we have come to call these Puritan Separatists the Pilgrims. The Pilgrims dropped anchor in what is now Provincetown harbor along Cape Cod; then, after sending out a band of armed men to explore the region, established their settlement in Plymouth, Massachusetts (Mayflower History, "Massasoit Ousemequin").
Four months later, in March 1621, Massosoit Sachem, who ruled jointly with his brother Quadequina over a tribe of the Wampanoag Nation, decided to visit the new settlers and enter into a treaty. Reasons for the treaty have been identified by historians as being two-fold. First, the Wampanoag Nation had already lost two-thirds of its population due to epidemics brought by European settlers in 1616. Second, the Wampanoags were being attacked by the neighboring Native American nation of Rhode Island called the Narragansetts. Therefore, in order to attempt to preserve more lives of the Wampanoag Nation, Massasoit felt it would be beneficial to enter into a treaty with the English settlers due to the strength of the settler's weaponry and arsenal. In addition, the Pilgrims entered into the treaty to gain help from the Native Americans in learning how to survive (Indian Country Today: Media Network, Toensing, "Native History: First Wampanoag-Pilgrim Treaty Signed on April Fools'").