Between my hostel and the main entrance to the HSA east compound was a large lot, overgrown with weeds and surrounded by a concrete wall. The rumor was that it was a mass burial ground and that the locals believed that it was haunted by restless spirits, bad juju or something.
I don't intend to dig very deeply into the history of modern East Asia, but one version of what may have happened there can be found in George H. Kerr's book, Formosa Betrayed. There are those who disagree with at least some of the events described in this book, but it's generally agreed that those were difficult times for all concerned.
All I know for sure is that I lived right next to that plot of ground for fifteen months and the only spirits I ever saw were in cans or bottles and the only screeching I ever heard was from the normal panic stops of Taipei traffic.