I wonder, was the sun disk too close to Japan or part of the old imperial regime because both the Communist and Republicanist avoided it and Nationalist only sort of adopted it later.

The colors of the Five Race Flag are the Han, Manchus, Mongols, Hui Muslims, and Tibetans.

I don't know much about the Japanese occupation of Manchuria, but if they built it up like they did Korea and Taiwan, then China owes a lot of gratitude. (Similar to the way the British influence in Shanghai and Hong Kong benefits the PRC still)

My guess is the Five Race flag was an attempt to imitate the European tricololors — it would be interesting to study the moving geographies of flag designs!

According to the wikipedia page [1] the colors of the Five Race flag are Red for Han, Yellow for Manchu, Blue for Mongol, White for for Hui Muslims, and Black for Tibetan. The China Since 1912 page [2] agrees, except it reverses the symbolism for White and Black.

It's my understanding that the Japanese built up Manchuria pretty rapidly — the same feat they accomplished for the Koreans (especially the northern part of the country) and the Taiwanese. I'm not sure how they treated the Manchus and Manchurian Chinese before the war — Japanese treatment of Koreans and Taiwanese were pretty well [3], but of course Japan owned Manchuria for much less time.

I wondered about the Japan connection too, but as that didn't stop the North or South Koreans from implementing it [4], it would seem strange to abandon a cultural symbol because an enemy appropriated it.

Thanks for the comment!

[1] http://en.wikipedia.org/wiki/Five_Races_Under_One_Union
[2] http://tmg110.tripod.com/china1.htm
[3] http://www.tdaxp.com/archive/2005/12/11/the-commonwealth-of-korea-and-japan-shintaro-ishihara-right.html
[4] http://www.tdaxp.com/archive/2006/11/11/borat-vexillogical-learnings-of-asia-to-make-benefit-gloriou.html