It is obvious that many elements in "The Old Republic" are wildly anachronistic. Especially the Sith Empire seems to be primarily a copy of the Galactic Empire, projected into the past by the author. (Moffs and Grand Moffs, pseudo-Star Destroyers, core world accent, the title Emperor instead of Dark Lord, an Emperor that looks suspiciously like Palpatine etc.) Species like Chiss and Kaleesh appear, despite first contact with them being still millennia in the future. The Jedi Order seems more post- than pre-Ruusan.

So is there any historical basis to it or is it an entirely fictional story?

Additional question: What is known about the political views of the author? At first the story seemed like thinly veiled criticism of Palpatine to me, but they paint the Republic in a pretty bad light as well, so I'm confused.