From the Wikipedia page [1]
The Province of the Transvaal (Afrikaans: Provinsie van die Transvaal), commonly referred to as the Transvaal (/ˈtrɑːnsvɑːl, ˈtræns-/; Afrikaans: [ˈtransfɑːl]), was a province of South Africa from 1910 until the end of apartheid in 1994, when a new constitution subdivided it. The name "Transvaal" refers to the province's geographical location to the north of the Vaal River. Its capital was Pretoria, which was also the country's executive capital.
In 1994, after the fall of apartheid, the former provinces were abolished, and the Transvaal ceased to exist. The south-central portion (including the PWV) became Gauteng, the northern portion became Limpopo and the southeastern portion became Mpumalanga. Most of the North West came from the southwestern portion of the old Transvaal, and tiny segment of the Transvaal joined KwaZulu-Natal. However, even before 1994 the Transvaal Province was subdivided into regions for a number of purposes (such as municipal and district courts, and sporting divisions). These divisions included Northern Transvaal (present-day Limpopo and Pretoria), Eastern Transvaal (currently Mpumalanga), Western Transvaal (currently part of North West Province) and Southern Transvaal (now Gauteng Province).