What was the political significance of dynastic marriages?

The essence of such marriages is that the rulers, thus, could establish good relations between their countries for a future period of time. Also, such an alliance could settle a long conflict between states. Thus, dynastic marriages became tools for finding new allies or ending contradictions between states. For example, Prince Svyatoslav was married to an Ugrian princess at the insistence of Princess Olga. This was the reason that Hungary and Russia were allies.