The ancient challenge system to inoffice officials in our country became matured in times of the Tang and Song Dynasties. Its maturity showed itself in the following ways: First, special decrees were introduced for inoffice officials to avoid their relations. Secondly, the avoidance scope was more extended than before, involving nearly every matter of government, such as imperial examination, selection of officials, limits of authority, avoidance of relations and whatever. Thirdly, special regulations were established to appoint officials out of offspring and relations of consort relatives, imperial families, and powerful subjects, restricting the growth of their influence. Finally, the ancient exchange system was introduced to inoffice officials avoiding their relations. The maturity of the challenge system to inoffice officials played an active role in rectifying administration of officials and preventing corruption.

imperial examination； avoidance of inoffice officials; replacement examination; employing a relative in office; avoidance of relations; the exchange system