The three had a long chat, with Obama being introduced to Ndesandjo's wife, a native of Henan, China, whom he married a year ago.

"I'm frightened for my son' s future, " said a migrant from Henan.

He squatted down to talk to local farmers to offer them help to see them through a severe drought that now plagues Henan and six other provinces in northern and central China.

Mr. Chen's blog entries were sometimes their own desperate pleas: Lovelorn girls of Henan where are you? read one.

Mr Wang' s results suggest, for example, that the people of Beijing, Shandong, Hubei, Guangdong, Chongqing and Henan are China' s foodies, spending more on dining than the national average.