Historically, marriage has been "regulated" by religion: various Christian denominations had their specific rites and requirements, as did Jews, Muslims, Hindus, etc. If the Hindus allowed children to marry, the Christians didn't go up  in arms against it. If the Muslims contracted polygamous marriages, the Jews would shrug it off, and so forth. There were frictions at timesbut they mostly arose out of either conquest or proselytism, not in the daily lives of ordinary people.  

It was only with the monumental social upheaval brought about by the French revolution that government sought an interest in regulating marriage. The slaying of priests and the burning of Catholic churches in France at the end of the 18th century created a void of ecclesiastical authority which the French revolutionary government moved in to fill. As the church had been the pivotal center of the life of ordinary French citizens up to that point, the government sought for itself no lesser of a role, including the ceremonials and, more importantly, the legalization of the crucial events of family life - marriages, births and deaths.

Slowly but surely, governments all over the world moved into the realm of family life and started setting standards for contracting marriage. At first they were minimal: the minimum age of consent and/or the requirement of parental blessing, monogamous marriage, and dowry provisions. However, things were to get more complex quickly....