It is a shame how ethnocentric education is, but it reflects the ethnocentric nature of mankind. It is not simply African philosophy and culture that is neglected, but also many others, including Asian and Indian. This contributes to our abysmal ignorance in international diplomacy and business, and the key to solving this problem clearly does lie in education, the earlier the better.
However, there are many forces that work against this. For example, textbook publishers create social studies textbooks based upon the needs and politics of the largest states, usually Texas and California, because this maximizes their sales. Those textbooks are often then distributed nationally, which means that the greatly ethnocentric and even racist politics of Texas are presented as "history" across the country. Another force that makes it difficult to solve the problem is that of the local nature of education. The state may set curriculum, but each local school board pours content into that curriculum, thus assuring that its own prejudices are perpetuated.
It is up to teachers, and maybe even up to students, to see to it that other cultures are attended to, not simply in social studies, but across the curriculum. How many students even know that some of our greatest concepts in math are from an Arabic culture? Should we not be reading literature from other cultures in our English classes? Are not the ideas of Hinduism and Buddhism of value to us? As busy as we are and as much ground as we have to cover, there is no excuse for our neglect of the rest of the world.