Britain and it's territories and the Afrikaner republics of Transvaal and the Orange Free State.
fought from October 11, 1899, to May 31, 1902, between Great Britain and the two Boer (Afrikaner) republics—the South African Republic (Transvaal) and the Orange Free State
credit : www.Britannica.com
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the rub-al-khali is also known as the arabian desert and the "empty quarter"