Major countries, such as the United States, Japan, and China have already recognized the potential of Africa’s markets. Korea has also taken notice of Africa's diverse export markets recently. However, Africa is comprised of 53 different countries and, as a result, entry into the region poses a formidable strategic challenge. Korean authorities and export groups have suggested a “3 plus 2 Country Strategy” in order to make inroads into the African region. This paper contributes to discussions of this strategy by comparing the effects of economic growth in South Africa and Nigeria on Sub-Saharan Africa. In addition, because economic power in Africa is concentrated in a small number of countries, whose market characteristics are different from those of integrated unions, the determinants of economic growth in Africa as a whole and unions may be different. This paper investigates whether or not this is, in fact, the case. The empirical results can be summarized as follows: First, the effects of South Africa’s economic growth on Sub-Saharan Africa and the SADC (a representative union of South Africa) are much larger than the effects of Nigeria’s growth on Sub-Saharan Africa and the ECOWAS (a representative union of Nigeria). These empirical results imply that the preferred country to pursue economic cooperation with is South Africa. Second, we confirm that determinants of economic growth are different for Africa and the unions. The main determinant of growth in African countries may be the population ratio, but in the SADC, growth appears to be determined by ratio trade volumes of GDP. Finally, we also find that the ratio investments of GDP have a positive influence on the economic growth of both Africa and SADC.