 As a result, there is pressure on land use, which has resulted in people migrating from the highlands to the woodlands in the northeastern region.The "Socio geographic units" of the Matengo originally consisted of a political organization which was "non-hierarchical, comprising a collectivity of sovereign matrilineal groups of equivalent status and diverse origins.Each such patrilineal group ("kilau") represented the descendants of a common grandfather, who during his lifetime had been the unquestioned leader ("matukolu" or "bambo") of the group."