SR SUNTOUR inc. is based in Chang Hua, Taiwan.
I believe that the story of SR SUNTOUR begins in Japan in 1987, when a large Japanese engineering company called Mori Industries bought SR (Sakae Ringyo, a once leading Japanese manufacturer of chainsets). SR was in financial straights as a result of the devastating combination of the rising dominance of Shimano and the strength of the Yen. In 1988 Mori took the obvious step and established a factory in Taiwan.
I also believe that in 1992 Mori bought SunTour, which was in exactly the same condition as SR had been, and for exactly the same reasons. That very same year manufacturing of some derailleurs was started at the Taiwan factory. The company then became known as SR SUNTOUR - continuing the SunTour tradition of using capital letters in unusual ways.
In 1999 SR SUNTOUR was floated on the Taipei stock Exchange and became a properly Taiwanese company.
Over the last decade SR SUNTOUR has developed a very successful business manufacturing suspension forks that are largely sold as original equipment to bicycle manufacturers. They are effective, reliable, no-nonsense products fitted on hundreds of thousands of mid-to-low-end mountain bikes.
In terms of derailleurs, SR SUNTOUR seems to have started out making low-end derivatives of SunTour designs - a move down market that SunTour had already begun before the takeover. In the late 1990s, however, SR SUNTOUR became more ambitious and started to produce more innovative and higher spec designs. Their particular area of interest seems in straightening out the cable routing - in a distant echo of the SunTour Superbe Tech design.
I have been told that SR SUNTOUR may have recently decided to stop manufacturing rear derailleurs, and are concentrating their efforts on other components.