Complex sentence: The Dulcinian movement began in 1300 when Gherardino Segalello founder of the Apostolics sect was burned in Parma, a brutal repression of the movement followed and his followers had to hide to save their lives.
Split into simpler sentences: The Dulcinian movement began in 1300 when Gherardino Segalello, founder of the Apostolics sect, was burned in Parma. A brutal repression of the movement followed and his followers had to hide to save their lives.