Why had Japan cut off contact with Tang China at the end of the 9th century?

It is supposed that the missions ceased because conditions had become too unstable in Tang and because Japan no longer found it necessary to import aspects of Tang culture or conduct diplomacy with its neighbors. The emergence of an East Asian trade network may have played a part as well.

Explanation:

answer; /// slavery should be outlawed in the new country, was part of the initial draft of the declaration of independence, but not part of the final

i know number 8 is something about only using 3/5 of the slave votes.