Not only in Africa but in few Asian countries too it is happening with women.  In the regions where education level is low i.e. illeteracy is higher; in those areas people are backward.  Their thinking is also affected by the illiterate environment.  Women leteracy ratio is much much lower in comparison to men's.  Under such circumstances women are not allowed to go outside their houses.  So they remain backward.
Also there are some religions which do not give liberty women and keep them in home only.
Though with the passage of time; the situation is improving.