“Oh, Mr Greenfield…!”
I was right there with you, Count.
My first guess would have been Hmong also. I had a friend in high school that Hmong in an arraigned marriage. Her marriage was arraigned at the age of 6 (he was 14), though she was very pleased that her parents didn’t want her to marry until she was 18, and were very adamant that if this marriage was not acceptable for her then she was within her rights to refuse. She did like the man though, they had been spending entire summers together and they were introduced at family functions and such as a couple, since she was 10 and he was 18 though she did stress that nothing untoward happened until she was married. They were second cousins, and she told me that cousin marriages were common. On her 18th birthday, she was married, and went to live at her husbands house, and there was expected to care for his parents and his extended family. I was aghast, but she didn’t see anything odd by it and liked her new family very much. Though, she did say that a few of her friends and cousins that were in similar situations did not have such a good outcome, and hated their marriages but were stuck by tradition. She was relatively old to go and live with her husband and she said that usually happened at 11 or 12.
I have had a patient once who was talking about her recent 10th anniversary party with her sisters. The woman was 23 at the time and had an 8 year old son. When I did the math I will admit I felt reaaaaallly squicky when her husband came in for his exam, though they did seem as loving as any other happy couple I have seen.
When I asked my friend why it seemed the women married very young but not the men she told me that in her culture women were thought to mature earlier than men and were able to run a household better earlier. When I visited her at her home with her inlaws the situation did not seem abusive, just very very different. The men of the house didn't do housework, or care for the children or such and were served first at meals, but, the women were the ones who ruled the roost. All the men were deemed good to do was work, play with the children, and heavy house work, like fixing the roof. The women were in charge of everything else such as finances, house hold decisions (what sofa do we buy and when), the children and everything else. The person who seemed to be the most respected was the great grandmother, and her word was law. The men seemed to enjoy doting on their wives with gifts, and playing with their children. Maybe this was the odd one out of early arraigned marriages, but it seemed to work for them.Looking for a change in your life, eh Astro? 
You might want to start dating first… marriage is a big step. 
Hey, it happens, but in the end, our laws trump their (past) culture.
Others have mentioned the Hmong. When they first came here, there were a number of stories about 10-14 year old girls being married off to men in their 30’s, with resulting prosecutions. The Hmong protested that it was simply a part of their culture. The answer was that it was a part of their culture, but that in their new country, such things were illegal and damn well WOULD be prosecuted.
While I’m sure that the transition wasn’t without it’s problems, and that the practice still happens to some extent, the people and their culture adapted.
And so will the Oaxacans. Or they’ll wind up in jail, or deported, or decide to becomes Mormons and move to rural Utah…or something.
Not to mention “soda and gatorade”.
From the link:
What a dumb Dad. Where does he think that an 18 year old is going to come up with that kinda scratch? Hasn’t he heard of the credit crunch? You know how hard it is to get a loan for a child bride in this economy?
Exactly so. Oaxaca state, in particular, has leagalized the concept of “usos y costumbres”, which essentially means that counties (municipios) have greater leeway than before in writing their laws (this mainly pertains to county elections, but it also further enshrines the policy of letting indigenous-dominant “agrarian communities” do their own thing – even though there is no legal distinction in Mexico between indigenous land or persons and other land or persons).
As you can imagine, this sort of thing fosters debate among, say, anthropologists and inigenous-supporting activists, who are torn between promoting cultural diversity and upholding the universal rights of women and children.