The area known as Tyannuntasachta (Endless Hills) in the language of the Six Nations was purchased from the Iroquois in 1749. It became part of Lancaster County which had been formed out of Chester County in 1729. Chester County was established by William Penn in 1682.
The Delaware Indians called the endless hills area Kittochtinny. The southern most ridge is now called Kittatinny. It is also know as First Mountain and Blue Mountain. The Delaware called what is now Stony Creek Sinne-hanna (stony stream).
Moravian missionaries moved into the area in the 1750s. They called the area St. Anthony's Wilderness.
Dauphin County, named for the son of Louis XVI of France, was separated from Lancaster County on March 2, 1784.
Lebanon County was separated from Dauphin County on February 16, 1813.