Heqin

Heqin, also known as marriage alliance, refers to the historical practice of Chinese monarchs marrying princesses — usually members of minor branches of the ruling family — to rulers of neighboring states.

Lou Jing, the author of the policy, proposed granting the eldest daughter of Emperor Gaozu of Han to Modu Chanyu of the Xiongnu. His proposal was adopted and implemented with a treaty in 198BC, following the Battle of Baideng two years prior. Wang Zhaojun of the Han dynasty and Princess Wencheng of the Tang dynasty are among the most famous heqin princesses.