Yea, I think they were considered "Taiwan" series. Probably got mostly funded by Taiwan companies.
But I think it still gets aired like a major series in the Mainland. In 1998/1999, Taiwan productions (or TVB for that matter) were generally considered "superior" to mainland ones. Of course, that was back in the days when Taiwan/TVB actually put effort into their series.
But then again, the "Tangren" of the late 90s was probably just Li Guo Li + buddies. I'm sure it was in combo with other production companies for funding. I mean, most certainly, the Tangren of today is much wealthier than the Tangren 10 years ago.