Islam retained clans and often tribes whereas Europe moved towards nuclear families. In Europe, significant social and political relationships were based on oath rather than kinship, whether between lords and followers (‘feudalism’) or among householders in city communities. Church and 'umma remained as universal societies. In Europe, territorial units of government became more entrenched, and, unlike in Islam, the nation sometimes became a political unit. Islam was well-disposed towards commerce. In Europe, the idea of the corporation as a legal body with specific legitimate powers favoured the city-state. In both societies, social inequalities and classes were justified, in Christendom by the organic metpahor, in Islam by a theory of the four social ‘orders’.