Initially, the British followed a policy of non-intervention in relation between the Malay states.[19] The commercial importance of tin mining in the Malay states to merchants in the Straits Settlements led to infighting between the aristocracy on the peninsula. The destabilisation of these states damaged the commerce in the area, causing British intervention. The wealth of Perak’s tin mines made political stability there a priority for British investors, and Perak was thus the first Malay state to agree to the supervision of a British resident.[14] British gunboat diplomacy was employed to bring about a peaceful resolution to civil disturbances caused by Chinese and Malay gangsters employed in a political tussle between Ngah Ibrahim and Raja Muda Abdullah. The Pangkor Treaty of 1874 paved the way for the expansion of British influence in Malaya. The British concluded treaties with some Malay states, installing “residents” who advised the Sultans and soon became the effective rulers of their states.[28] These advisors held power in everything except to do with Malay religion and customs.[14]
Johore alone resisted, by modernising and giving British and Chinese investors legal protection. By the turn of the 20th century, the states of Pahang, Selangor, Perak, and Negeri Sembilan, known together as the Federated Malay States, had British advisors.[14] In 1909 the Siamese kingdom was compelled to cede Kedah, Kelantan, Perlis and Terengganu, which already had British advisors, over to the British.[14] Sultan Abu Bakar of Johor and Queen Victoria were personal acquaintances, and recognised each other as equals. It was not until 1914 that Sultan Abu Bakar's successor, Sultan Ibrahim accepted a British adviser.[citation needed] The four previously Thai states and Johor were known as the Unfederated Malay States. The states under the most direct British control developed rapidly, becoming the largest suppliers in the world of first