The same principle was applied to Africa and Asia after the withdrawal of European powers from those continents and in locations such as the Soviet Union whose former central governments fell and constituent states gained independence. In 1964, the Organisation of African Unity passed a resolution stating that the principle of stability of borders, the key principle of "uti possidetis", would be applied across the continent. Most of Africa was already independent and so the resolution was principally a political directive to settle disputes by treaty based on pre-existing borders, rather than by resorting to force. To date, adherence to the principle has allowed African countries to avoid border wars; the notable exception, the Eritrean–Ethiopian War of 1998–2000, had its roots in a secession from an independent African country, rather than a conflict between decolonized neighbours. On the other hand, the colonial boundaries often did not follow ethnic lines, which has contributed to violent and bloody civil wars among differing ethnic groups in many postcolonial (and postcommunist) countries, including Sudan, the Democratic Republic of the Congo, Angola, Nigeria, Uganda, Georgia, Azerbaijan, Moldova and the former Yugoslavia.