The city of Dubai is the main population center of the Emirate of Dubai, one of seven which joined to form the United Arab Emirates in 1972. Ruled since 1833 by the Al-Maktoum Dynasty, Dubai is located on a sheltered harbor and was already one of the principal ports on the Persian Gulf by the 1870s. In 1903 it became a major British port of call, and the city remained as a protectorate of Great Britain until the Trucial States were declared independent in 1971. Dubai was originally a small fishing town, and became prosperous through an economy based on pearls and international sea trade. By the beginning of the 20th century the city was famous for having one of the largest souks (markets) in Arabia. In 1966 the discovery of oil in the region brought a new era of prosperity to Dubai. Today its economy is diversified, with oil taking a back seat to trade and manufacturing. Its free trade policies distinguish it from the other emirates within the nation, making it a special economic zone somewhat like Hong Kong. Today the city of Dubai is one of the wealthiest and most modern anywhere, boasting the highest skyline in the Middle East including the two of the tallest hotels in the world. It attracts a booming tourist business, drawn in part by major sporting events including horse races, boat races, tennis matches, and air shows. It is also a major shopping destination and an extremely international city, where only one quarter of the population consists of native Emiratis.