Nicholas Kristof's column in the New York Times today contains a sentence about the Chinese "goddess of mercy," Guanyin (Kwan yin), that I don't think is accurate. But maybe Kristof is right and I'm wrong. Kristof writes,
When the first Westerners arrived and brought their faith in the Virgin Mary, China didn’t have an equivalent female figure to work miracles — so Guan Yin, the God of Mercy, underwent a sex change and became the Goddess of Mercy.
You may know that Guanyin is a manifestation of the Bodhisattva Avalokiteshvara. My understanding is that until the time of the early Sung Dynasty (960–1126), the bodhisattva was portrayed in art as male. From the 12th century on, however, in much of Asia, Avalokiteshvara took the form of a mother-goddess of mercy.
During this time there were Nestorian Christians living within the Mongol Empire, but I don't believe the Nestorians venerated Mary. All the reference books says the first Catholic missionary to China was John of Montecorvino (1294-1328), who arrived in China in the early 14th century, when a female Guanyin was already well established in Chinese Buddhist iconography. For this reason I don't think there was a direct connection between Guanyin and Mary.
However, it is interesting to me that during the 10th through 12th centuries, when the image of Guanyin was becoming popular, the veneration of Mary also was on the rise in Europe. Was there some cultural cross-pollination the historians don't know about? Or some other factor that made mother goddesses particularly appealing during that time?