Based on this, the North Sung and Koryo started up a familiar intercourse;on the contrary, the Liaos with entirely different culture could only keep the tributary relations with Koryo by power.

• 北宋与高丽即是在此基础上展开友好交往，而文化迥异的辽却只能借助强权来维持其与高丽的朝贡关系。