Kuwait is believed to have been part of an early civilization in the 3rd millennium B.C. and to have traded with Mesopotamian cities. Archeological and historical traces disappeared around the first millennium B.C. At the beginning of the 18th century, the 'Anizah tribe of central Arabia founded Kuwait City, which became an autonomous sheikdom by 1756. 'Abd Rahim of the al-Sabah became the first sheik, and his descendants continue to rule Kuwait today. In the late 18th and early 19th centuries, the sheikdom belonged to the fringes of the Ottoman Empire. Kuwait obtained British protection in 1897 when the sheik feared that the Turks would expand their hold over the area. In 1961, Britain ended the protectorate, giving Kuwait independence, but agreed to give military aid on request. Iraq immediately threatened to occupy the area, and the British sent troops to defend Kuwait. Soon afterward, the Arab League sent in troops, replacing the British. Iraq's claim was dropped when the Arab League recognized Kuwait's independence on July 20, 1961. Historically, Kuwait followed a neutral and mediatory policy among Arab states.