Swayamvar or swayamvaram is an ancient Indian custom mentioned in the Ramayana and Mahabharatha (and no longer in practice in modern India). Nowadays swayamvar is taken to mean wedding.
It is a custom by which a bride-to-be (mostly a princess) selects her husband. Usually an auspicious date is fixed. On that day, all eligible men from far and wide come to the country of the princess. The eligible men can range from kings and princes to paupers. The princess then goes around inspecting them (much like the Head of the State who inspects the guard of honor) with a flower garland in her hand. When she reaches the man who catches her fancy, she puts the garland on him and they are supposedly married. That's all! So simple! There can be variations also. The King can put some criteria for deciding the abilities and skills of his daughter's husband. I think that was like a preliminary test to sift the husk. For example, Draupadi's father had put the criteria that he would give his daughter's hand to only that man who could shoot his arrow correctly at the eye of a rotating fish which was perched high in the centre of the royal court and that too only by looking at the image of the fish in a pond . (Talk about shooting the semen in the right direction!).
Sometimes if the princess is already in love with a young man, then the swayamvar makes it a lot easier for her. (Yes, even in ancient India girls had to be secretive about her love affairs).
That was the age of the princes and princesses.