The Great Trek is the name given to the exodus of 12,000–14,000 Boers from British Cape Colony. Frustrated by the colony’s Anglicization policies, restrictions on slave labour and population pressures intensified by drought and increasing inward migration, they chose to look for better grazing pastures elsewhere. After crossing the Orange River, the trekkers split, northwards or eastwards. After a series of skirmishes, the northern trekkers achieved decisive victory over the Ndebele at Mosega in 1837 and created the independent republics of Transvaal and Transorangia. The eastwards Boers defeated the Zulus at the Battle of Blood River and declared the republic of Natal. The British Government annexed Natal in 1843, but recognized the inland republics in 1852–54. However, they sought to restrain the Boer expansion by simultaneously granting recognition to two native protectorates in Griqua and Basuto. These territories harboured many Boer settlers, becoming a source of future contention.