Few townships in Pennsylvania are as rich in history as Tredyffrin Township, which is located at the easternmost edge of Chester County, Pennsylvania. In the center of the Township lies the rich and fertile Great Valley, beginning at Valley Forge and running west toward Coatesville. The earliest settlers were Welsh, and to them, the Township owes its name. Ten or Tre is the Welsh word for town or township, and Dyffrin means a wide cultivated valley; from these words comes the compound tre yr dyffrin, or Tredyffrin, meaning a township in a wide cultivated valley.

The Township had its beginning in 1682 when a group of Welsh Quakers went to William Penn in England and purchased, at a price of ten cents an acre, forty thousand acres of land in southeastern Pennsylvania. Penn promised the Quakers that here they could enjoy their customs and language in a little "barony" of their own. This land was originally known as the Welsh Tract and included within its boundaries parts of nine subsequent townships in four counties.

By 1707, Tredyffrin's population was large enough for it to be incorporated as a township. After they had cleared their land and established farms, the most pressing requirements for the early settlers became a mill to grind grain, a meetinghouse for their spiritual needs, and a market where they could sell produce. An example of meeting these needs was the construction of the Great Valley Mill, one of Tredyffrin's first mills. It was in operation by 1710, possibly even earlier, and was built by Thomas Jarman, a noted preacher and miller, on 300 acres of land by Valley Creek (it is now located on North Valley Road in Malvern.