Simplify the following text for a Grade 11 native English-speaking person.
Original: Only seven tragedies have survived intact : The Persians , Seven against Thebes , The Suppliants , the trilogy known as The Oresteia , consisting of the three tragedies Agamemnon , The Libation Bearers and The Eumenides , together with Prometheus Bound ( whose authorship is disputed ) .
Simplified: Only six tragedies have survived intact : The Persians , Seven against Thebes , The Suppliants , the trilogy known as The Oresteia , consisting of the three tragedies Agamemnon , The Libation Bearers and The Eumenides . There is also the play Prometheus Bound , but this was probably written by someone else .