Matrilineal and bilateral systems of land inheritance advantaged women in many respects, especially in granting them economic and social security, and considerable autonomy and equality in marital relations. These systems, however, did not remain fixed over time. Interventions by the colonial and post-colonial States, particularly in the legal and economic spheres, and the complex processes of social and cultural change which these set in motion, eroded customary practices. The large joint family estates came to be partitioned; formerly egalitarian tribal societies grew economically differentiated; there was an increasing penetration of market forces; there were notable shifts in the techniques of production, the social division of labour, and land relations; sexual mores altered; and patriarchal ideologies spread in influence. Women, in particular, were profoundly affected by these changes. At the same time, their customary exclusion from major authority in public bodies meant that they were unlikely to be the ones directing the change, and were seldom in a position to effectively protect their interests.