In times of the Shang and the Zhou Dynasty, social grassroot organizations were made up of numerous clans, whose unity and union were an important part of the current social relation. The unity and union of clans in those days took three main forms, including mutual marriage, military union and political unity, of which political unity was the tribal key policy to external relations, assuming different kinds of unity between the imperial families of the Shang and the Zhou court and heterofamilies. A close concern and study of those different kinds of unity and union between clans will play an important part in deeply understanding the social relation and social structure in the Shang and the Zhou Dynasty.

Times in the Shang and the Zhou Dynasty； unity of clans； union of clans