 In 1943 the Japanese beheaded Tengku Rachmadu'llah, a member of the royal family of the Sultanate of Serdang.In the 1943–1944 Pontianak incidents (also known as the Mandor Affair), the Japanese orchestrated a mass arrest of Malay elites and Arabs, Chinese, Javanese, Manadonese, Dayaks, Bugis, Bataks, Minangkabau, Dutch, Indians, and Eurasians in Kalimantan, including all of the Malay Sultans, accused them of plotting to overthrow Japanese rule, and then massacred them.The Japanese falsely claimed that all of those ethnic groups and organisations such as the Islamic Pemuda Muhammadijah were involved in a plot to overthrow the Japanese and create a "People's Republic of West Borneo" (Negara Rakyat Borneo Barat).