This holiday is always celebrated on 16 September. It is also known as ' Hari Malaysia'
It commemorates 16 September 1963, when the former British colony of Singapore and the East Malaysian states of Sabah and Sarawak, joined the Federation of Malaya to create the Malaysian Federation.
Singapore only remained in the federation for two years, leaving on 9 August 1965.
Originally this date was planned for 1 June 1963, but it was delayed twice; once to 31 August to make it coincide with an older national day, and then delayed again to allow referendums to take place in certain regions.
Malaysia Day has only been a national holiday since 2010. On announcing this holiday, Prime Minister Datuk Seri Najib Tun Razak said the day would involve activities that would foster the Malaysia spirit and would be celebrated with formal events such as a parade to commemorate the historical moment. He added that it should remind the Malaysian people about their struggle in achieving independence.
On 31 August, Malaysians celebrate Independence Day (Merdeka Day), so it is unusual for a country to effectively have two independence day holidays.