African nationalism in the colonial era was often framed purely in opposition to colonial rule and was therefore frequently unclear or contradictory about its other objectives. According to historian Robert I. Rotberg, African nationalism would not have emerged without colonialism. Its relation to Pan-Africanism was also ambiguous with many nationalist leaders professing Pan-African loyalties but still refusing to commit to supranational unions. African nationalists of the period have also been criticised for their continued use of ideas and policies associated with colonial states. In particular, nationalists usually attempted to preserve national frontiers created arbitrarily under colonial rule after independence and create a national sense of national identity among the heterogeneous populations inside them.