On historical evolution of pre-perm community in the Middle Ages

There is almost three hundred years period of time in archaeological culture of the Cheptsa ancient settlement history which cannot be explained by archaeological data and one of such settlements is Idnakar. The population of unknown language membership disappeared there in XII century but wriiten sources of the XVI century show direct ancestors of present-day northern Udmurts. Historian V. S. Churakov who studied the censuses of that time had traced the migration of specific patronymies to the Cheptsa from the Lower Vyatka since XVcentury. In this polemic article the author's own hypothesis based on some other sources of land settlement of that territory is substantiated.