1. Mirzakhani is the first Iranian 2. Bhargava is the first Canadian 3. Hairer is the first Austrian 4. Avila is the first Brazilian
So, I understand instead that you're identifying this as notable for the following reason:
There are 100 times more women in the world than Canadians, yet women and Canadians have the same number of Fields Medals.
But my general feeling is that there used to be a few "powerhouse" countries and institutions that dominated, but that has been changing for many years. There's a lot more diversity these days. So I think kiyoto's point speaks to the changes there.
In 1950, it would have been pretty inconceivable that a woman from Iran would have had the access and opportunities to contribute to mathematics in a way that would have earned a Fields medal; in 2014, it's a first-time feat; hopefully, in the future, it quickly becomes mundane.
^suspect this is incorrect.
http://www.newsweek.com/surprising-success-irans-universitie...
We don't hear about it much, but Iran has one of the best universities in the world.
The medal is not just Artur brilliance and hard work, but also due to the IMPA: http://www.impa.br/ A sixty years old institution that gathered Brazil best mathematicians and gave Artur the resources to become a great researcher. Brazil had to cultivate and invest in this institution for decades.
Iran has great universities: http://www.newsweek.com/surprising-success-irans-universitie... The Medal is is probably just crowning their hard work.
The outcome of this is simple: you'll have selected top N individuals from an exam of half a million people and put them in a single school. Of course you're going to see those people shine. That says _nothing_ about the absolute quality of what that school gives you, just how good it is relative to its peers in the country, and I define quality as "output - input". The "input" is high quality, but the delta is merely meh in my opinion. Also, the students are high quality--the faculty are generally not (unlike what's mentioned in the article), but they do end up taking some credit.
In terms of the contribution of the country, I can just say that she is a survivor of an accident years ago, where seven talented math students died, whom had similar achievements to hers at the time. Overall, the contribution of the country to its mathematicians has been negative, specifically so to the female ones.
Since 1990, at least one Fields Medal winner has worked in France -- until this year. France has a culture of supporting mathematics and mathematicians. It has its quirks and difficulties, but national support for research has played an important role.
If some one is good enough to win Fields medal every one and every thing around works more like friction to their overall direction. And that's true for every country in the world.
What you say doesn't make sense as she went to a very good Iranian school..
[0]http://en.wikipedia.org/wiki/Mu%E1%B8%A5ammad_ibn_M%C5%ABs%C...
EDIT - I'm not trying to be funny, her hairstyle makes her look like she has a receding hairline so I thought she was a man.