All these were groups organised on the basis of the special professions pursued by the members of each respective group, although many of the groups might consist eventually of persons of homogeneous blood. Besides these groups there was another kind based solely on identity of blood, that is to say, on the principle of racial affinity. When we examine the circumstances of the formation of such groups, we generally find that a body of immigrants at a certain period was constituted as a group by itself by way of facilitating the administration. Sometimes several bodies of immigrants, differing as to the period of immigration, were formed into one large corps. In the corps thus formed, there would have naturally been people of various occupations, connected only by blood relationship. The third kind of group was quite unique in the motive of its formation. It was customary in ancient times in Japan to organise a special group of people in memory of a certain emperor or of some noted member of the imperial family. This happened generally in the case of those personages who died early and were much lamented by their nearest relations. Sometimes, however, a similar group was formed in honour of a living emperor. As it was natural that groups thus formed paid little attention to the consanguinity of their members, it is presumable that they might have consisted of persons of promiscuous racial origin. On the other hand, it is also clear that there could be no necessity for conglomerating intentionally men of heterogeneous racial origin in order to effect a mixture of blood between them. Such a motive is hardly to be considered as compatible with the spirit of the age in which the scrutinising of genealogies was an important business. Added to this, the organisation of a group out of people of different stocks would have incurred the danger of making its administration exceedingly difficult. As to the profession pursued by persons belonging to such a group, any generalisation is difficult. Some groups might have been organised mainly from the need of creating efficient agricultural labour, in order to provide for the increasing necessity of food stuffs; in other words, from the need for the exploration of new lands. Other memorial groups might have been formed for the sake of providing for the need of various kinds of manual labour, and must have contained men of divers handicrafts and professions, so as to be able to provide for all the daily necessities of some illustrious personage, to whom the group was subject. When men of promiscuous professions formed a group and produced sundry kinds of commodities, the custom of bartering must have naturally arisen within it, but the stage of bartering in a market, periodically opened at a certain spot, such as is described in the _San-kuo-chih_, must have been the result of a gradual development. Moreover, it would be a too hasty conclusion to say that such a group was a self-providing economic community.