Socially acceptable age for marriage varied from tribe to tribe in ancient times but in most cases it was based on the appearance of pubic hair on boys and menarche in girls.

In Islam, Muhammad married his first wife when she was 6 but reportedly did not consummate it until she was 9. Though whether or not this counts is debated. Muhammad did do things with Aisha that Arabic has a word for that English does not. We would equate the act to basically being a thigh-job, but this is a named and accepted practice in the Qur’an.

Jewish oral tradition determined boys were too young until they were 14 and had signs of puberty or until they turned 20, unless they show signs of impotence. Impotence rendered a boy unable to ever become a man until 35. Girls were the same, except their younger age limit was 13 plus one day.

Roman law required girls to be at least 12 and marriages from the age of 12-24 required approval of the father of the bride.

Catholic canon law was based on the Roman law originally but was changed in the 1100s to allow boys and girls as young as 14 and 12 respectively to marry without parental consent. Canon law recognized the age of consent as 7. Medieval Eastern European tradition allowed girls to be married as young as 12-15 with menarche. England created the first recorded age-of-consent law in 1275 but it described the offense as being against a “maiden within age”. Some experts interpret that to mean 12 years old which was the age of marriage at the time.

http://www.faqs.org/childhood/A-Ar/Age-of-Consent.html

http://www.jewishencyclopedia.com/articles/10861-minority

http://www.jewishencyclopedia.com/articles/10888-mi-un

https://web.archive.org/web/20150904002714/https://www.aeaweb.org/assa/2006/0106_0800_1104.pdf

https://books.google.com/books?id=WVEjYPaeuTgC&pg=PA53&redir_esc=y#v=onepage&q&f=false