u/Fair_Cobbler8616

I was wondering why the "official" split of the Empire is considered 395 with Theodosius's sons? There were co-emperors since 364 with Valentinian and Valens after the reunification of the Empire in 363 with Jovian. I know there were rebellions and usurpers during Theodosius's reign but I was hoping someone could clarify it a bit for me. I'm fairly new into Roman history so sorry if this is a stupid question lol. Thanks!