Of all the Arabic epic poems that have been popular at various times, only Sirat Bani Hilal is still publicly performed.
Evidence
Of all the Arabic epic poems that have been popular at various times, only Sirat Bani Hilal is still publicly performed.
Furthermore, while most other epics were only recited, Sirat Bani Hilal has usually been sung.
Conclusion
The musical character, therefore, is the main reason for its longevity.
Evaluate
The argument establishes a correlation a play still being performed publicly and being sung. But to assert that the relationship is causal goes too far.