 Epaminondas's role in the conflicts of the 4th century is also described, much later, by Diodorus Siculus, in his "Bibliotheca historica".Diodorus was writing in the 1st century BC, and is also very much a secondary source, though useful for corroborating details found elsewhere.Epaminondas was born into the Theban aristocracy in the late 5th century BC; estimates for the year of his birth vary widely.