The year 1870 in the history of the Cape Colony marks the dawn of a new era in South Africa, and it can be said that the development of modern South Africa began on that date. Despite political complications that arose from time to time, progress in Cape Colony continued at a steady pace until the outbreak of the Anglo-Boer Wars in 1899. The discovery of diamonds in the Orange River in 1867 was immediately followed by similar finds in the Vaal River. This led to the rapid occupation and development of huge tracts of the country, which had hitherto been sparsely inhabited. Dutoitspan and Bultfontein diamond mines were discovered in 1870, and in 1871 the even richer mines of Kimberley and De Beers were discovered. These four great deposits of mineral wealth were incredibly productive, and constituted the greatest industrial asset that the Colony possessed.