Task: Question Answering
Input (English): Passage: Valley View is a mid-19th-century Greek Revival residence and farm overlooking the South Branch Potomac River northwest of Romney, West Virginia. Valley View is atop a promontory where Depot Valley joins the South Branch Potomac River valley.
The Valley View property was part of the South Branch Survey of the Northern Neck Proprietary, a large tract that was inherited by Thomas Fairfax, 6th Lord Fairfax of Cameron, in 1719. It was settled by John Collins and his family in 1749, and acquired by the Parsons family before 1772. The Valley View house was built by James Parsons Jr. in 1855. After the Civil War, Parsons' widow sold the farm to Charles Harmison. His wife, Elizabeth Harmison, inspired by her childhood Virginia home, Western View, and the scenic South Branch Potomac River views, named the farm Valley View. The most recent of a series of owners, the Mayhew family, bought the property in 1979. Valley View's current proprietors, Robert and Kim Mayhew, have restored the historic residence and grounds.
The house at Valley View is a two-story brick structure with a rectangular architectural plan. The front entrance is covered by a small portico, topped with a pediment supported by wooden Doric columns. The rear of the house, with a two-story wood porch stretching across it, faces the South Branch Potomac River valley and Mill Creek Mountain. Each of the original eight large rooms of the 1855 structure contains a fireplace framed by a wooden trabeated mantelpiece with classical elements. The original windows, wooden trim, and materials in the main section of the house are intact. The house was listed on the National Register of Historic Places in 2012 as a locally significant example of Greek Revival architecture. 
Question: What is the name of the large tract that was inherited by the 6th Lord Fairfax of Cameron?
Output (English): the Northern Neck Proprietary.