On April 1, 1621 – from This Day in History at History.com:
At the Plymouth settlement in present-day Massachusetts, the leaders of the Plymouth colonists, acting on behalf of King James I, make a defensive alliance with Massasoit, chief of the Wampanoags. The agreement, in which both parties promised to not “doe hurt” to one another, was the first treaty between a Native American tribe and a group of American colonists. According to the treaty, if a Wampanoag broke the peace, he would be sent to Plymouth for punishment; if a colonist broke the law, he would likewise be sent to the Wampanoags.
In November 1620, the Mayflower arrived in the New World, carrying 101 English settlers, commonly known as the pilgrims. The majority of the pilgrims were Puritan Separatists, who traveled to America to escape the jurisdiction of the Church of England, which they believed violated the biblical precepts of true Christians. After coming to anchor in what is today Provincetown harbor in the Cape Cod region of Massachusetts, a party of armed men under the command of Captain Myles Standish was sent to explore the immediate area and find a location suitable for settlement. In December, the explorers went ashore in Plymouth, where they found cleared fields and plentiful running water; a few days later the Mayflower came to anchor in Plymouth harbor, and settlement began.
The first direct contact with a Native American was made in March 1621, and soon after, Chief Massasoit paid a visit to the settlement. After an exchange of greetings and gifts, the two peoples signed a peace treaty that lasted for more than 50 years.