The name Siwanoy may be a corruption of Siwanak, 'salt people'. They spoke Munsee, a Delaware language. Their closest allies were the Mahicans to the north, with whom they shared a totem - the “enchanted wolf”, with the right paw raised defiantly. The Siwanoys' largest village in 1640 was Poningo, located near modern-day Rye, New York. They also had stockade settlements at Anne’s Hoeck, Hunter Island, and Davenport Neck, and kept “winter quarters” farther south at Hell Gate. They referred to the area surrounding Anne's Hoeck and Hunter Island as Laaphawachking. Two glacial erratic boulders named Grey Mare and Mishow, located on Hunter Island, were spiritually significant to the Siwanoy. Here the Siwanoys practiced their sacred ceremonies, and two sachems are believed to be buried at Mishow; the Siwanoys believed the boulders to have been placed there by their guardian Manitou. However, many Siwanoys likely becamed Christianized; the Siwanoy sagamoreWampage I was one of these, and he took John White as a baptismal name.
Conflicts with European colonists
The western bands of the Wappinger, including the Siwanoy, became involved in war with the Dutch in 1640, which lasted five years; this period is often referred to as Kieft's War, and is said to have cost the lives of some 1,600 Wappinger refugees. Thus, tensions between the colonists and the Native Americans were extremely high at this time, and this undoubtedly led to the massacre of Anne Hutchinson and her family in 1643. A group of Siwanoy, led by Wampage I, killed Hutchinson, six of her children, and nine others in August 1643, near Split Rock, an ancient landmark. The only survivor was Hutchinson's nine-year-old daughter, Susanna - possibly spared because of her red hair - who "became the wife of an Indian Chief, residing in a settlement near the Split Rock". It has been written that Wampage himself was the murderer of Hutchinson and that he adopted the name of Anhõõke due to a Mahican custom of taking the name of a notable person personally killed.
Following the 1654 treaty, the Siwanoys remained in the area around Westchester County for another hundred years, until they eventually "melted away" by intermarriage with the English settlers. Some continued to reside along the shore in Westchester County until 1756, when most of the Wappinger and Mahicans remaining in the area joined the Nanticoke, then living under the protection of the Iroquois, and with them were eventually merged into the Lenape. Some of them joined the Stockbridge Indians, who were removed to Wiconsin in the 1830s.