The earliest exploration of the area was led by Captain Watkin Tench in 1789. The origin of this name puzzled historians for many years because the clue lay not in Blacktown City but on Norfolk Island. Governor Philip Gidley King had been in charge of the first settlement there in early 1788 and had noted that the hillside where he had built his Government House had been difficult to dig owing to the amount of tree roots beneath the surface. The hill on Norfolk became known as Rooty Hill and the name is now official.Rooty Hill Road, Kingston, Norfolk Island, Google Maps, accessed 7 March 2013 When King returned to New South Wales he built the headquarters for his government reserve of 1802 at the foot of a hill that reminded him of the Norfolk Island Rooty Hill and used the same name. The name Rooty Hill first appeared on a map in 1803.
