The reasons for the mass emigration from the Cape Colony have been much discussed over the years. Afrikaner historiography has emphasized the hardships endured by the frontier farmers which they blamed on British policies of pacifying the Xhosa tribes. Other historians have emphasized the harshness of the life in the Eastern Cape ,which suffered one of its regular periods of drought in the early 1830s, compared to the attractions of the fertile country of Natal, the Orange Free State and the Transvaal. 

  Growing land shortages have also been cited as a contributing factor. The true reasons were obviously very complex and certainly consisted of both push  factors including the general dissatisfaction of life under British rule and pull  factors including the desire for a better life in better country.

  The Voortrekkers were mainly of Trekboer migrating farmer, descent living in the eastern frontiers of the Cape. Hence, their ancestors had long established a semi-nomadic existence of trekking into expanding frontiers.Voortrekkers migrated into Natal and negotiated a land treaty with the Zulu King Dingane. Upon reconsideration, Dingane doublecrossed the Voortrekkers, killing their leader Piet Retief along with half of the Voortrekker settlers who had followed them to Natal.

  Other Voortrekkers migrated north to the Waterberg area, where some of them settled and began ranching operations, which activities enhanced the pressure placed on indigenous wildlife by pre-existing tribesmen, whose Bantu predecessors had previously initiated such grazing in the Waterberg region. These Voortrekkers arriving in the Waterberg area had believed they were in the Nile River area of Egypt based upon their understanding of the local topography.

  Andries Pretorius filled the leadership vacuum hoping to enter into negotiations for peace if Dingane would restore the land he had granted to Retief. When Dingane sent an impi armed force, of around twelve thousand Zulu warriors to attack the local contingent of Voortrekkers in response, the Voortrekkers defended themselves at a battle at Nacome River called the Battle of Blood River, on 16 December 1838 where the vastly outnumbered Voortrekker contingent defeated the Zulu warriors. 

  This date has hence been known as the Day of the Vow as the Voortrekkers made a vow to God that they would honor the date if he were to deliver them from what they viewed as almost insurmountable odds. The victory of the besieged Voortrekkers at Nacome River was considered a turning point. The Natalia Republic was set up in 1839 but was annexed by Britain in 1843 whereupon most of the local Boers trekked further north joining other Voortrekkers who had established themselves in the region.

   Armed conflict, first with the Ndebele people under Mzilikazi in the area which was to become the Transvaal, then against the Zulus under Dingane, went the Voortrekkers' way, mostly because of their tactics, their horsemanship and the effectiveness of their muzzle-loading guns. This success led to the establishment of a number of small Boer republics, which slowly coalesced into the Orange Free State and the South African Republic. These two states would survive until their annexation in 1900 by United Kingdom during the Second Boer War.The Voortrekkers are commemorated by the Voortrekker Monument located on Monument Hill overlooking Pretoria, the erstwhile capital of the South African Republic and the current and historic administrative capital of the Republic of South Africa. Pretoria was named after the Voortrekker leader Andries Pretorius.

  The Voortrekkers had a distinctive flag, used mainly by the Voortrekkers who followed Andries Hendrik Potgieter, which is why it was also known as the Potgieter Flag. This flag was used as the flag of the Zoutpansberg Republic until this republic was incorporated into the Transvaal Republic also known as the South African Republic. A version of this flag was used at Potchefstroom, one of the first independent Boer towns and republics established by local Voortrekkers.

  The Boer Republics sometimes also referred to as Boer states, were independent self-governed republics created by the northeastern frontier branch of the Dutch-speaking proto Afrikaans, inhabitants of the north eastern Cape Province and their descendants variously named Trekboers, Boers, Afrikaners and Voortrekkers, in mainly the northern and eastern parts of what is now the country of South Africa.

   Although some of these republics were already founded from 1795 onwards during the period of Dutch colonial rule at the Cape, most of these states were established after Britain took over from the Netherlands as the colonial power at the Cape of Good Hope. Subsequently a number of its Dutch-speaking proto-Afrikaans often called "die taal" the language, inhabitants trekked inland in 1835 in order to escape British administrative control in a movement that became known as the Great Trek. Several of these states were established after military defeats of the local population by the Voortrekkers/Boers by virtue of their technologically superior weaponry.

  The Voortrekkers usually skirted the most densely populated areas, trekking into largely depopulated areas which were the result of the Mfecane or Difaqane initiated by the Zulu King Shaka in the 1820s. When the Voortrekkers encountered locally established groups nations, they tended to opt to negotiate, turning to warfare only when attacked.The Voortrekkers under the leadership of Piet Retief obtained a treaty from the Zulu King Dingane to settle part of the lands the Zulus administered or held sway over, but Dingane later changed his mind, killing Retief and 70 members of his delegation.

  Dingane's impis Zulu warriors, then went on to kill almost 300 Voortrekkers who had settled in the Natal region.After Andries Pretorius was recruited to fill the leadership vacuum created by the deaths of Piet Retief and Gerhard Maritz, he initially offered to negotiate for peace with Dingane if he were to restore the land he had initially offered to Retief.Dingane responded by attacking the Voortrekkers; on 16 December 1838 the battle of Nacome River  ,later named the Battle of Blood River occurred, during which 300 Voortrekkers survived and won a decisive battle against thousands of Dingane's impis.

  The Natalia Republic was established in 1839 by the local Boers after Pretorius entered into an alliance with Mpande, the new Zulu king.The territories north of the Vaal River in the Transvaal were officially recognized as independent by Great Britain with the signing of the Sand River Convention on 17 January 1852.The territories and districts of the Transvaal were Potchefstroom, Lydenburg and Zoutpansberg, which united in 1857 to form the South African Republic.

   The Orange Free State was recognized as independent by Great Britain on 17 February 1854. The Orange Free State became officially independent on 23 February 1854 with the signing of the Bloemfontein or Orange River Convention. The Orange Free State was nicknamed the model republic. 

    The New Republic comprising the town of Vryheid  was established in 1884 on land given to the local Boers by the Zulu King Dinuzulu the son of Cetshwayo after he recruited local Boers to fight on his side. The Boers were promised and granted land for their services & were led by Louis Botha who would go on to prominence during the second Anglo-Boer War.

   This republic was later absorbed into the Transvaal/South African Republic.States were also established by other population groups, most notably the Griqua, a subgroup of South Africa's heterogeneous and multiracial Coloured people. Most notable among these were Griqualand West and Griqualand East.While some of these were mini-states which were relatively short-lived, some, especially the Transvaal and the Orange Free State, developed into successful independent countries which along with Britain were also officially recognized by the Netherlands, France, Germany, Belgium and the United States.

   These two countries continued to exist for several decades, despite the First Boer War with Britain. However, later developments, including the discovery of diamonds and gold in these states, led to Second Boer War. In this war, the Transvaal and Orange Free State were defeated and annexed by the overwhelmingly larger British forces, officially ceasing to exist on 31 May 1902, with the signing of the Treaty of Vereeniging. A new British colony, the Union of South Africa, was subsequently established, in which the Transvaal and the Orange Free State became provinces along with the Cape and Natal.