The Native American Siwanoy or Sinanoy were a band of Algonquian-speaking people, the Wappinger, in what is now the New York City area. By the mid-17th century, when their territory became hotly contested between Dutch and English colonial interests, the Siwanoy were settled along the East River and Long Island Sound between Hell Gate and Norwalk, Connecticut, a territory that included eastern parts of what became the Bronx and Westchester County in New York and southwestern Fairfield County in Connecticut.
The first European settler to the territory was Jonas Bronck, who had arrived in New Netherland in 1639, and negotiated the purchase of 254 acres of land along the Harlem River in what is today's Mott Haven.
They are known for their massacre of Anne Hutchinson and her family during Kieft's War in 1643. In August 1643, a group of Siwanoy led by the sachem Wampage massacred Hutchinson's household of 16 people near Split Rock, an ancient landmark. The only survivor was Hutchinson's nine-year-old daughter, Susanna, who may have been spared because of her red hair. The attack was in revenge for New Netherland governor Willem Kieft's February massacres of Wappinger refugees from Wecquaesgeek at Corlaer's Hook and Pavonia. Like thousands of American Indians and numerous colonists, Hutchinson became caught up in the bloody reprisals which characterized the two year conflict. The Siwanoy attack killed Hutchinson, six of her children, and nine others.
On June 27, 1654, Thomas Pell, a Connecticut physician, obtained title to a large amount of Siwanoy territory in New York through a treaty with a number of sachems, including Wampage. This included the Pelham Islands and parts of the mainland Bronx and coastal Westchester. New Netherland authorities did not recognize his title. They accused the New Englanders of continued encroachment upon Dutch territory. Pell's coup turned out to be decisive in New York history. A militia of his colonists from Minneford Island (present-day City Island) supported the English naval invasion force that conquered New Amsterdam in 1664.
- Anne Hutchinson an English dissenter murdered by the Siwanoy in the year 1643.