Seneca is historically the largest of the Six Nations and holds the westernmost position in the Confederacy's image of itself as a single longhouse, giving Seneca, together with Mohawk in the east, the title Keepers of the Doors, and seating Seneca as one of the two Elder Brother nations on the Grand Council. William Fenton's political history of the confederacy assigns Seneca eight chief titles among the fifty the founding five nations divided among themselves, fewer than some smaller nations by strict count but carrying outsized influence in practice as the westernmost check on the Confederacy's diplomacy toward other Indigenous nations and, later, toward colonial New York and Pennsylvania.
Seneca territory in western New York was the last and hardest hit by the 1779 Sullivan Campaign, which burned Seneca towns as thoroughly as it burned Cayuga's, and Seneca land continued to shrink through treaty and purchase across the following two centuries. The Seneca Nation of Indians and the Tonawanda Band of Seneca hold reservations in New York today, and Seneca families also live at Six Nations of the Grand River in Ontario. The Longhouse religion carried by the whole Confederacy was itself reformed by a Seneca prophet, Handsome Lake, in the early nineteenth century, and Seneca communities remain closely identified with the religion's ongoing practice; its medicine societies, including the False Face healing societies shared across the Confederacy, restrict their knowledge to initiated members, and the atlas does not set out their content.