The Trucial States ( ; also known as Trucial Oman, Trucial States of the Coast of Oman, the Trucial Coast, and Trucial Sheikhdoms) were a group of sheikhdoms in the south eastern Persian Gulf, previously known to the British as the 'Pirate Coast', which were signatories to treaties (hence 'trucial') with the British government. These treaties established an informal protectorate by Great Britain and the sheikhdoms, or emirates, were a British protectorate from 1820 until 2 December 1971, when the seven principal trucial sheikhdoms became independent. Six (Dubai, Abu Dhabi, Sharjah, Ajman, Umm Al Qawain and Fujairah) were to form the United Arab Emirates on that day; the seventh – Ras Al Khaimah – joined the Federation on 10 February 1972.