Although the idea itself predates Malaysian independence, the phrase "ketuanan Melayu" did not come into vogue until the early 2000s decade. Historically, the most vocal political opposition towards the concept has come from non-Malay-based parties, such as the Malaysian People's Movement Party (Parti Gerakan Rakyat Malaysia) and Democratic Action Party (DAP); in the 2000s decade, the multiracial People's Justice Party (Parti Keadilan Rakyat, or PKR) also positioned itself against "ketuanan Melayu", advocating instead "ketuanan rakyat" (supremacy of the people). The idea of Malay supremacy gained attention in the 1940s, when the Malays organised themselves to protest the Malayan Union's establishment, and later fought for independence. During the 1960s, there was a substantial effort challenging "ketuanan Melayu" led by the People's Action Party (PAP) of Singapore — which was a state in Malaysia from 1963 to 1965 — and the DAP after Singapore's expulsion. However, the portions of the Constitution related to "ketuanan Melayu" were "entrenched" after the race riots of 13 May 1969, which followed an election campaign focused on the issue of non-Malay rights and "ketuanan Melayu". This period also saw the rise of "ultras" who advocated a one-party government led by UMNO, and an increased emphasis on the Malays being the "definitive people" of Malaysia — i.e. only a Malay could be a true Malaysian.