(b)(i) Historical factors: These have contributed to the variation in the population density in West Africa because ancient cities that developed like Kano, Katsina, Timbuktu are due to trans-saharan trade which took place several years ago. The population of these areas grew because of natural defence during war and being the sites of traditional empires those days
(ii) Agricultural activities tend to have possible effects on population distribution e.g the eastern Nigeria, part of Ashanti developed with high population because of intensive agricultural activities due to fertility of the soil, but where the land is not fertile, people tend to abandon such areas
(iii) Mining; The presence of minerals in certain areas tends to attract high population because of availability of jobs and other facilities in the areas
(iv) Industrialisation. People tend to move to places where there are many industries , as these will help to provide job and improve the standard of living of the people.