What did the three Greek tragedians (Sophocles, Aeschylus, Euripides) base their plays on?

Greek tragedy is a form of theatre from Ancient Greece and Anatolia. It reached its most significant form in Athens in the 5th century BC, the works of which are sometimes called Attic tragedy.

Greek tragedy is widely believed to be an extension of the ancient rites carried out in honor of Dionysus, and it heavily influenced the theatre of Ancient Rome and the Renaissance. Tragic plots were most often based upon myths from the oral traditions of archaic epics. In tragic theatre, however, these narratives were presented by actors. The most acclaimed Greek tragedians are Aeschylus, Sophocles, and Euripides. These tragedians often explored many themes around human nature, mainly as a way of connecting with the audience but also as way of bringing the audience into the play.

what lesson are you referencing?