Sharjah is a major port city and the third-most populous city in the United Arab Emirates, after Dubai and Abu Dhabi. It is the capital of the Emirate of Sharjah and forms part of the Dubai-Sharjah-Ajman metropolitan area. The emirate shares legal, political, military and economic functions with the other emirates of the UAE within a federal framework. Each emirate has jurisdiction over some functions such as civil law enforcement and provision and upkeep of local facilities. Sharjah has been ruled by the Al Qasimi dynasty since the 18th century.