What about Japan? I think they have the highest amounts of 100+ year olds. Fuck it, google:
Record 20,000-plus Japanese over 100 years old
2003-09-09
The number of Japanese aged at least 100 rose to 20,561 this year, a new record in the world's longest-living nation, the government said Tuesday.
[...]
Japan's life expectancy is the longest in the world for both sexes _ 85.23 years for women and 78.32 for men in 2002 _ and the growing number of people who have lived more than a century is a source of national pride.
[...]
About 84 percent of Japan's centenarians are women, including the country's oldest living person, Kamato Hongo, who turns 116 on Sept. 16. The second oldest is a man, 114-year-old Yukichi Chuganji.
[...]
Okinawa, a chain of islands on Japan's southern fringe, boasts the country's highest proportion of people over 100: 34.67 per 100,000. Local specialties include vegetables, fruits and bean curd.
http://chinadaily.com.cn/en/doc/2003-09/09/content_262672.htm
Must be genetics, diet and I'm sure like you said, peaceful/simple lifestyles (seems that most of these old folks are away from the busy mainland).