On 17 January 1852 the United Kingdom signed the Sand River Convention treaty with approximately 5 000 Boer families, recognizing their independence in the region to the north of the Vaal River (Transvaal).
This laid the foundation for the Zuid-Afrikaansche Republiek (South African Republic) that was to be established later in 1852.
Source: http://www.sahistory.org.za/