About a decade ago, some Chinese propagandists were encouraging calling Okinawa the Ryukyu kingdom and trying to ferment an independence campaign. It didn’t get too far.

Ryukyu was an independent kingdom with its own ruling court, language, culture etc until 1872, when it was annexed by Japan. Quite a few Okinawans would rather like to return to the previous state of affairs, although probably not if it involves exchanging the Japanese yoke for the Chinese one. (Ryukyu was a Qing tributary, but the Qing had bigger problems on their hands than worrying about a bunch of small islands.)

Not "ferment". "Foment".