the three maritime features belong to the same rock body. History Pedra Branca was known to sailors for centuries. Part of the Chinese sailing instructions for the South China Sea based on information compiled by Admiral Zheng He (1371–1433) advised a navigator that after departing Long Ya Men (Mandarin for "Dragon's Teeth Gate"), a rocky outcrop at the gateway to what is now Keppel Harbour in Singapore, he should steer a course of between 75° and 90° for five watches until his vessel reached Baijiao. Pedra Branca was also mentioned in Dutch voyager Jan Huyghen van Linschoten's Itinerario (Itinerary), an account of his voyages in the Portuguese East Indies. After the publication of the work in 1596, the island began appearing regularly on European maps of the Far East. The 1598 English edition of the work stated: Pedra Branca was originally within the territory of the Johor-Riau Sultanate, which was founded in 1528 by Sultan Alauddin Riayat Shah II, the son of Sultan Mahmud Shah of the Malacca Sultanate. In the mid-17th century, the Dutch Governor of Malacca wrote to the Dutch East India Company, asking it to send two boats to the Straits of Singapore to "cruise to the south of Singapore Straits under the Hook of Barbukit and in the vicinity of Pedra Branca" to stop Chinese traders from entering Johor River. The plan was put into force, and two Chinese junks were captured in the Straits and diverted to Malacca. However, this action provoked a protest from the Sultan of Johor, which showed that the Sultan regarded the junks' seizure as an infringement of his sovereignty in the area. Three letters written in 1824 to the Government of India by the British Resident in Singapore, John Crawfurd, also confirm it was his understanding that all the islands in the region of the Straits of Singapore came under the Johor Sultanate. In addition, other 19th-century documents show that the Sultan of Johor exercised authority over the Orang Laut ("sea people") who inhabited the maritime areas of the Straits of Singapore and visited Pedra Branca. One of these was a letter of November 1850 by John Turnbull Thomson, the Government Surveyor of Singapore, which reported on the need to exclude the Orang Laut from Pedra Branca where Horsburgh Lighthouse was being built. Calling them a "half fishing half piratical sect", Thomson noted that they "frequently visit the rock so