Complex sentence: Associated with the cabaret and folk theatre, it has had an aura of being a theatre of, by, and for the people, and has flourished in oppressive governments as a means of actual underground communication and spreading of critical thought.
Split into simpler sentences: Associated with the cabaret and folk theatre, it has offered itself as a theatre of, by, and for the people. In this guise, political theatre has developed within the civil societies under oppressive governments as a means of actual underground communication and the spreading of critical thought.