
The Straits Settlements were just a minor but important part of the total and consisted of trading hubs Malacca, Dinding, Penang and Singapore. From 1837 until 1867 these were administered by the East India Company, who also used the settlements as a penal colony for Indians. Their sometimes brutal rule was replaced by colonial rule after protests by both locals and British politicians. The remainder of Malaya was divided into the Federated Malay States and Unfederated Malay States, all of which were British protectorates.

North Borneo, now the eastern part of Malaysia, was dominated by the Sultanate of Brunei until the 1840's. Various British expeditions to control piracy in the region resulted in the Brunei Sultanate losing most of its territory and becoming a protectorate itself in 1888. The north east part of Borneo became the crown colony British North Borneo and the south east part became a protectorate in 1841 known as Sarawak and ruled by an Englishman named Charles Brooke which started The White Rajahs dynasty.
During WW2 the Japanese conquered and occupied all of the British territories in the region.
All Malaya & Borneo territories, except Brunei, formed the Union of Malaya & British Borneo in 1948 and became the Federation of Malaysia in 1963. Singapore, home to many Chinese, was often in conflict with the Malay-dominated federation and was expelled in 1965 forming the Republic of Singapore.
Currency
Spanish Dollars were commonly used in South East Asia from the 17th century, and mixed with local tin and copper coins. In 1825 Pound Sterling was made the official currency throughout the British Empire, but this was soon abandoned as Spanish Dollars remained the preferred silver coinage in both the West and East Indies. In 1837 the EIC introduced the Rupee in the Straits Settlements at 0.48 Spanish Dollars.
The Rupee however never became commonly used and the Spanish Dollar remained the preferred currency. Small change denominated in cents was issued specifically for the Straits Settlements from 1841 for use in all Malay & Borneo territories. From the 1860's the Hong Kong Dollar became widely used in the Straits and from this the Straits Dollar was officially split off in 1898 with a separate currency board establishing in Singapore. The Straits Dollar and its successors circulated also in Malaya, Sarawak, Brunei and North Borneo, even though the last three also issued some local coins next to it.
The depreciation of silver relative to gold caused the Straits Dollar to drop from 4s2d to 2s4d by 1906, from when it became pegged to Sterling. In 1939 the Strais Dollar was renamed Malayan Dollar. With North Borneo and Sarawak joining the Union of Malaysian the currency was renamed again to Malayan & British Borneo Dollar in 1954. These existed until 1967 when Malaysia & Singapore adopted their own Dollars. That same year Brunei opted to join Singapore in a currency union.
The Sterling peg at 2s4d (£7 = 60 Straits Dollars) stayed in force until 1967. Before WW2 a Straits Dollar was therefore worth $0.56, and with Sterling devaluations of 1945 and 1949 dropped to $0.42 and $0.33 respectively. A Malaysian Ringgit is now worth around $0.24 and a Singapore Dollar $0.70, reflecting the relative strength of the Singapore economy over the past decades.
Coins
Various Malay states issued their own coins until the early 19th century. In 1841, the first EIC issues were struck for the Straits Settlements in copper quarter, half and one Cents. In the 1870's small silver coinage was added and later half Dollars and Dollars. The Malayan Dollar only had denominations from 1 to 20 Cents, and after WW2 only in base metal. Malaya & British Borneo saw the return of a 50 Cents coin.
Catalogue
Malay Peninsula:
https://en.numista.com/catalogue/peninsule_malaise-1.html
Straits Settlements:
https://en.numista.com/catalogue/straits-1.html
Malaya:
https://en.numista.com/catalogue/malaya-1.html
Malaya & British Borneo:
https://en.numista.com/catalogue/malaya_borneo-1.html
Brunei:
https://en.numista.com/catalogue/brunei-1.html
Sarawak:
https://en.numista.com/catalogue/sarawak-1.html
British North Borneo:
https://en.numista.com/catalogue/borneo-1.html