 However, Penn soon realized that he needed to purchase the land from the Native Americans to maintain clear ownership.Penn advertised throughout Europe, offering parcels of land for 40 shillings, subject to a rent of one shilling per annum forever.In 1737, Penn's sons expanded their land holdings to include most of the Lehigh Valley through the “Walking Purchase.” Although the Lenni Lenape did not think this was a legitimate claim, they eventually moved out of the area, allowing Europeans to settle it.