The Krios are descendants of the following groups of freed enslaved Africans:
The Black Poor, who arrived from England in 1787 and 1788, many of whom had fought with the English during the American War of Independence, but were now mainly destitute in England.
The Nova Scotian Settlers, who had been enslaved in America, escaped captivity to fight with the British during the American War of Independence. They were then evacuated to Nova Scotia in 1783 and then resettled in Sierra Leone in 1792.
The Trelawny Maroons, who had originally been exiled to Nova Scotia after the second Maroon war in Jamaica were resettled in Sierra Leone in 1800. The Negro Americans brought directly from America to Sierra Leone by Paul Cuffee in 1816. The Liberated Africans, who make up the largest group of ancestors, were brought to Sierra Leone between 1808 and 1863 after the British had abolished the slave trade and intercepted slave ships in the high seas of the Atlantic. They make up over 90% of Krios. Finally, the West Indian Regiment disbanded in Sierra Leone in 1819 and 1821 are also part of the Krio ancestry.