There are many marriages between families. At that time, almost any big family was a marriage. This was common before the Song Dynasty, when the imperial examination was not perfect. For example, Liu Bei and Sun Shangxiang in Romance of the Three Kingdoms can be regarded as the marriage of Sun Liu Group.
As for the in-laws between countries, there are many, such as Wang Zhaojun, Princess Wencheng, Songzan Gambu and so on.
Relevant records and poems, such as Wang Zhaojun's "When Princess Ming first left the Han Palace, tears wet her temples. Depressed and colorless, the king still can't hold himself "and so on.