The Native American people more commonly refereed to as "Delawares" because they lived in the area of the Delaware River from its source in New York down through Pennsylvania and New Jersey to Delaware. This is the tribe of Indians which inhabited the area of Treasure Island in the Delaware River where the Order of the Arrow was founded and also the Main Line where Paoli 1 is located. Horseshoe is located on the fringe of Lenape territory near where they bordered the Susquehannock. Therefore, this tribe is the base for many OA ceremonies and pageants.

Lenni Lenape is the term they called themselves. It means "Real People" and thus the shortened version "Lenape" means simply people. The Lenape are a subgroup of the larger Algonquin dialect peoples of the Northeastern United States. Within the Lenape language, there were several sub-dialects as well. Unami is the dialect of the southern groups which inhabited the area of Southeastern Pennsylvania.