On to the Twentieth Century: The British extended their control over the peninsula by putting together the whole panoply of colonial administration — civil service, public works, judiciary force, police force, post office, education, and land regulation — with teams of British administrators, teachers, engineers, and doctors to go with it. At the same time, the tin industry, dominated by Chinese using labor-intensive methods in the 19th century, passed increasingly into Western hands, who employed the modern technology of gravel pumps and mining dredges. Petroleum had been found in northern Borneo, at Miri, and in Brunei, and the Anglo-Dutch Shell company used Singapore as its regional depot for its oil supplies and exports. But the major breakthrough for the Malay economy was the triumph of rubber, when Singapore's new garden director, Henry Ridle ("Rubber Ridley" to his friends, "Mad Ridley" to all doubting Thomases) had developed new planting and tapping methods and painstakingly spread his faith in rubber around the peninsula. World demand increased with the growth of the motor-car and electrical industries, and sky-rocketed during World War I. By 1920, Malaya was producing 53 percent of the world's rubber, which had overtaken tin as its main source of income. The Malay ruling class again took a back seat. Together with effective control of the rubber and tin industries, the British now firmly held the reins of government. The sultans were left in charge of local and religious affairs, content with their prestige, prosperity, and security. The census of 1931 served as an alarm signal for the Malay national consciousness. Bolstered by a new influx of immigrants to meet the rubber and tin booms of the 1920s, non-Malays now slightly outnumbered the indigenous population. The Great Depression of 1929 stepped up ethnic competition in the shrinking job market, and nationalism developed to safeguard Malay interests against the Chinese and Indians rather than the British imperial authority. Though hampered by the peninsula's division into the States and the Straits Settlements, relatively conservative Muslim intellectuals and community leaders came together at the Pan-Malayan Malay Congress in Kuala Lumpur in 1939. In Singapore the following year, they were joined by representatives from Sarawak and Brunei. Teachers and journalists urged the revival of the common Malay-Indonesian consciousness, split by the Anglo-Dutch dismemberment of the region in the 19th century. This spirit became a factor in the gathering clouds of war. 
Who was joined by representatives from Sarawak and Brunei in Singapore?
Conservative Muslim intellectuals and community leaders