Complex sentence: An old rumor in Karakol is that Przhevalsky was Joseph Stalins'father; it is based on the fact that Przhevalsky often stayed at the rooming house run by Stalin's mother and that he was quite a dashing fellow.
Split into simpler sentences: An old rumor in Karakol is that Prjevalsky was Joseph Stalins'father. This rumor is based on the fact that Prjevalsky often stayed at the rooming house run by Stalin's mother and that Prjevalsky was quite a dashing fellow.