The Pax Britannica of the 19th century resulted in British consolidation of trade routes, particularly those close to the British Raj. In response to piracy in the Persian Gulf region, the British deployed warships and forced much of the Persian Gulf States at the time (including Bahrain) to sign the General Maritime Treaty of 1820, which prohibited piracy and slavery. In 1861, the Perpetual Truce of Peace and Friendship was signed between Britain and Bahrain, which placed the British in charge of defending Bahrain in exchange for British control over Bahraini foreign affairs. With the ascension of Isa ibn Ali Al Khalifa as the Hakim of Bahrain in 1869, Manama became the centre of British activity in the Persian Gulf, though its interests were initially strictly commercial. Trading recovered fully by 1873 and the country's earnings from pearl exports increased by sevenfold between 1873 and 1900. Representing the British were native agents, usually from minorities such as Persians or Huwala who regularly reported back to British India and the British political residency in Bushehr. The position of native agent was later replaced by a British political agent, following the construction of the British political residency (locally referred to in ) in 1900, which further solidified Britain's position in Manama.