Qingchao waipan tizhi nei de chaojian nianban yu chaogong zhidu.

The Qing Dynasty distinguished the Mongolia, Xinjiang, Tibet frontier ethnic areas from the foreign countries beyond it borders viewing them as two different categories of internal and external suzerains. The Qing Dynasty establishes the annual pilgrimage system for the internal suzerains and continued the previously established tributary system for the external suzerains. This was the essential difference between the two systems.