The slavery system itself was officially incorporated in the national system under the ritsuryo system, but there had been a discrimination between Ryomin and Senmin before that time, and various kinds of limitations were put on Senmin.
奴婢制度そのものは、律令制によって正式に国家の制度に取り込まれるが、それ以前からも良民と賤民は区別されており、賤民はさまざまな制限を受けていた。