Chulalongkorn (r. 1868–1910) initiated centralisation, set up a privy council, and abolished slavery and the corvée system. The Front Palace crisis of 1874 stalled attempts at further reforms. In the 1870s and 1880s, he incorporated the protectorates up north into the kingdom proper, which later expanded to the protectorates in the northeast and the south. He established twelve "krom" in 1888, which were equivalent to present-day ministries. The crisis of 1893 erupted, caused by French demands for Laotian territory east of Mekong. Thailand is the only Southeast Asian nation never to have been colonised by a Western power, in part because Britain and France agreed in 1896 to make the Chao Phraya valley a buffer state. Not until the 20th century could Siam renegotiate every unequal treaty dating from the Bowring Treaty, including extraterritoriality. The advent of the "monthon" system marked the creation of the modern Thai nation-state. In 1905, there were unsuccessful rebellions in the ancient Patani area, Ubon Ratchathani, and Phrae in opposition to an attempt to blunt the power of local lords.