In The Birth of Tragedy, Nietzsche describes a Dionysian satyr as a force that impregnates an Apollonian world of images giving rise to dialogue on the Hellenic stage and henceforth the Greek tragedies. Is it that conflict between Dionysian and Apollonian ideas that gives rise to tragedy or is Greek tragedy a result of some other force, according to Nietzsche?
From 'The Dionysiac World View', which is a kind of commentary on BN it appears that Greek tragedy on Nietzsche's view arose from the conjunction, the fusing in creative conflict, of the Apollonian and the Dionysiac. Both mentalities had existed separately but 'at the moment when the Hellenic "Will" blossomed' and this conjunction occurred, tragedy was born. It is not clear that Nietzsche offers any other source or origin for tragedy except this conjunction. It is a fair inference that both the Apollonian and the Dionysian had existed separately before the birth of tragedy - but co-existed and not fused in the art of tragedy.
Quotation is from Nietzsche, 'The Birth of Tragedy and Other Writings', ed. R. Guess & R. Speirs, Cambridge, 2000, 119.