The journeyings and campings of the ancient people becomes intelligible when the make-up of the present pueblos is known. One finds that every pueblo consists of clans which are larger families of blood relations having certain duties and responsibilities together; a name, such as the bear, cloud, or century plant; certain rites and ceremonies to the beings; clan officers and customs amounting to laws, and a history preserved in the minds of the members. So it will be seen that a tribe among the house-builders is composed of a number of smaller tribes, called clans, each complete and able to take care of itself, forming the present villages. Often in the early days a powerful clan migrated long distances and left members in many different places, because clan law forbids marriage within the clan, and the man must live with the people of his wife. In these migrations portions of a clan would break off and cast their lot with other villages, and often several clans traveled in company, building their pueblos near one another, and thus came the groups of ruins so common in the Southwest. For this reason, all the present villages have received swarms from other hives and have sent out in turn swarms from the home village, during their slow migrations around the compass. The habits of the ancient people thus led to a constant flux and reflux in the currents of life in the Southwest and in spite of their substantial houses and works costly of labor the Pueblo Indians were as migratory as the tent-dwellers of the Plains, though they moved more slowly. Their many-celled villages on mesas or on the banks of streams, in the cliffs of the profound canyons, dug in the soft rocks or built in the lava caves, were but camps of the wanderers, to be abandoned sooner or later, leaving the dead to the ministrations of the drifting sand.