The first large-scale immigration wave to East Africa (excluding mercenaries) was in 1865. Since then, the number of immigrants has surged, and with the increase in East African transport capacity, the scale has grown larger and larger.
This means that the first batch of immigrants has settled in East Africa for nine years, and the nature of East African immigration has caused the current population to grow explosively.
This can be analogous to the German regions, where the fertility rate is currently quite high; East Africa's is even higher because East Africa bears the cost of childbirth, something not feasible in German regions.
German land resources have been divided by nobles and landlords. With the development of capitalist agriculture, the focus is no longer on labor and occupancy rates but on profitability as the top priority.
