Crown Colony of Sarawak in the context of "Borneo"

Singapore, officially the Republic of Singapore, is an island country and city-state in Southeast Asia. Its territory comprises one main island, 63 satellite islands and islets, and one outlying islet. The country is about one degree of latitude (137 kilometres or 85 miles) north of the equator, off the southern tip of the Malay Peninsula, bordering the Strait of Malacca to the west, the Singapore Strait to the south along with the Riau Islands in Indonesia, the South China Sea to the east and the Straits of Johor along with the State of Johor in Malaysia to the north.

In its early history, Singapore was a maritime emporium known as Temasek; subsequently, it was a major constituent of several successive thalassocratic empires. Its contemporary era began in 1819, when Stamford Raffles established Singapore as an entrepôt trading post of the British Empire. In 1867, Singapore came under direct British control as part of the Straits Settlements. During World War II, Singapore was occupied by Japan in 1942 and returned to Britain as a Crown colony following Japan's surrender in 1945. Singapore gained self-governance in 1959 and in 1963 became part of the new federation of Malaysia, alongside Malaya, North Borneo and Sarawak. Ideological differences led to Singapore's expulsion from the federation two years later; it became an independent sovereign country in 1965. After early years of turbulence and despite lacking natural resources and a hinterland, the nation rapidly developed to become one of the Four Asian Tigers.

Malaysia is a country in Southeast Asia. A federal constitutional monarchy, it consists of 13 states and three federal territories, separated by the South China Sea into two regions: Peninsular Malaysia on the Indochinese Peninsula and East Malaysia on the island of Borneo. Peninsular Malaysia shares land and maritime borders with Thailand, as well as maritime borders with Singapore, Vietnam, and Indonesia; East Malaysia shares land borders with Brunei and Indonesia, and maritime borders with the Philippines and Vietnam. Kuala Lumpur is the country's national capital, largest city, and the seat of the legislative branch of the federal government, while Putrajaya is the federal administrative capital, representing the seat of both the executive branch (the Cabinet, federal ministries, and federal agencies) and the judicial branch of the federal government. With a population of over 34 million, it is the world's 42nd-most populous country.

The country has its origins in the Malay kingdoms, which, from the 18th century on, became subject to the British Empire, along with the British Straits Settlements protectorate. During World War II, British Malaya, along with other nearby British and American colonies, was occupied by the Empire of Japan. Following three years of occupation, Peninsular Malaysia was briefly unified as the Malayan Union in 1946 until 1948 when it was restructured as the Federation of Malaya. The country achieved independence on 31 August 1957. On 16 September 1963, independent Malaya united with the then British crown colonies of North Borneo, Sarawak, and Singapore to become Malaysia. In August 1965, Singapore was expelled from the federation and became a separate, independent country.

The Colony of Singapore was a Crown colony of the United Kingdom that encompassed what is modern-day Singapore from 1946 to 1959. During this period, Christmas Island, the Cocos (Keeling) Islands, and Labuan were also administered from Singapore. Singapore had previously been established as a British colony since 1824, and had been governed as part of the Straits Settlements since 1826. The colony was created when the Straits Settlements was dissolved shortly after the Japanese occupation of Singapore ended in 1945. The power of the British Government was vested in the governor of Singapore. The colony eventually gained partial internal self-governance in 1955, and lasted until the establishment of the State of Singapore in 1958, with full internal self-governance granted in 1959.

After a few years of self-governance, Singapore went on to merge with Malaya, Sarawak and North Borneo (Sabah) to form Malaysia on 16 September 1963, thereby completely ending 144 years of British rule in Singapore. Due to differing views in dealing with political, economic and racial issues, Singapore would eventually cease to be a part of Malaysia and become an independent sovereign country on 9 August 1965.

The Malaysia Agreement, formally known as the Agreement relating to Malaysia between United Kingdom of Great Britain and Northern Ireland, Federation of Malaya, North Borneo, Sarawak and Singapore (MA63), is a founding document which provided for the union of North Borneo (Sabah), Sarawak and Singapore with the existing states of Malaya. This new political entity was to be known as Malaysia.

Signed in London, United Kingdom, the agreement came into effect on 16 September 1963, which is now commemorated as Malaysia Day. Less than two years later, Singapore was expelled from Malaysia following political and economic disagreements, becoming a sovereign state on 9 August 1965.

Malaya, officially the Federation of Malaya, was a country in Southeast Asia from 1948 to 1963. It succeeded the Malayan Union and, before that, British Malaya. It comprised eleven states – nine Malay states and two of the Straits Settlements, Penang and Malacca. It was established on 1 February 1948.

Initially a self-governing colony of the United Kingdom, Malaya became fully sovereign on 31 August 1957, and on 16 September 1963, Malaya was superseded by Malaysia when it united with Singapore, North Borneo (Sabah) and Sarawak. Singapore was expelled on 9 August 1965, leaving the original states of Malaya along with Sarawak and Sabah – now collectively known as East Malaysia – to form modern-day Malaysia, while the former Federation of Malaya is now referred to as Peninsular Malaysia or West Malaysia.

Singapore, officially the State of Singapore, was briefly one of the 14 states of Malaysia from 1963 to 1965. Malaysia was formed on 16 September 1963 by the merger of the Federation of Malaya with the former British colonies of North Borneo (Sabah), Sarawak and Singapore. This marked the end of 144 years of British rule in Singapore, which began with the founding of modern Singapore by Stamford Raffles in 1819. With a land area of approximately 670 km (260 sq mi), it was the smallest state but had the largest population and was highly urbanised, playing a central role in the national economy. As part of the integration referendum and the Malaysia Agreement, Singapore was given autonomous status including in education, labour and healthcare.

The merger was supported by the British, Malayan and Singaporean leaders as a measure to counter the influence of communism in Southeast Asia, especially through the Malayan Communist Party (MCP). The threat of communist expansion was considered serious by all parties, and the union was seen as a means to contain it through political consolidation. However, serious disagreements soon surfaced between the governments of Singapore and Malaysia, led by the People's Action Party (PAP) and the Alliance Party respectively. Conflicts arose over financial contributions, political participation and racial policies. Although a common market had been promised in exchange for Singapore's substantial tax revenues, trade barriers remained in place. In response, Singapore withheld development loans to Sabah and Sarawak. The situation was worsened when the Malay–based United Malays National Organisation (UMNO) of the Alliance and the PAP contested elections beyond their agreed jurisdictions, triggering further mistrust.

Independence Day (Malay: Hari Merdeka), also known as National Day (Malay: Hari Kebangsaan), is the independence day of the Federation of Malaya from the United Kingdom. It commemorates the Malayan Declaration of Independence of 31 August 1957, and is defined in article 160 of the Constitution of Malaysia. The day is marked by official and unofficial ceremonies and observances across the country.

The observation of 31 August as Malaysia's national day is the cause of some controversy, especially among East Malaysians, with calls to prioritise the celebration of Malaysia Day (Hari Malaysia) on 16 September instead. Malaysia Day commemorates the formation of Malaysia in 1963, when the four entities of North Borneo, Sarawak, Singapore and Malaya federated to form Malaysia as part of the Malaysia Agreement.

Malaysia Day (Malay: Hari Malaysia) is a public holiday observed nationwide on 16 September each year since 2010. It marks the anniversary of the signing of the Malaysia Agreement, which came into effect on that date in 1963 and led to the creation of Malaysia. The agreement brought together the Malaya (independent since 1957), North Borneo (later renamed Sabah), Sarawak and Singapore into a single federation. Singapore was later expelled from the federation on 9 August 1965, and Malaysia Day is no longer observed there.

In East Malaysia, many regard Malaysia Day as the country's true "national day", arguing that 31 August commemorates the independence of Malaya, which was a separate political entity to Malaysia.