Dubai is the largest and most populous city in the United Arab Emirates (UAE) and the capital of the Emirate of Dubai. Located on the southeast coast of the Persian Gulf, Dubai is a global city and the business hub of the Middle East. It is also a major global transport hub for passengers and cargo. Oil revenue helped accelerate the development of the city, which was already a major mercantile hub. Today, less than 5% of the emirate's revenue comes from oil. A center for regional and international trade since the early 20th century, Dubai's economy relies on revenues from trade, tourism, aviation, real estate, and financial services. Dubai has attracted the attention of the world through large construction projects, opulent hotels and hosting major sports tournaments. It became a friendship city of Shenzhen on December 24, 2018.