Zájù ("mixed entertainment" or "variety play") was a form of theatre extremely popular under the Yuán. Under the Mongol dynasty, Chinese culture, and especially written production of books, etc. was kept under heavy surveillance by the foreign overlords. As a result, much of Chinese culture (not only entertainment) went oral. The Yuán is the dynasty that saw the development of religious theatrical plays, which became an essential part of Chinese folk religion (see p39 of The Celestial Empire).
Zájù is one of these forms of art. It combines narrated and sung parts, with the addition of acrobatics, dance, singing, and mime. The roles are usually clearly recognisable, with recurring characters (the villain, the clown) recognisable by their flamboyant make-up.
Since the establishment of the Mongol dynasty has resulted in the abolition of the Civil Service Examination, scholars, physicians, and astrologers can be found in a zájù troupe. Unemployed scholars would write zájù librettos, known for the intricacy of their verse forms, not only to vent their frustration, but also for mere commercial reasons, as a class of nouveaux riches produced a constant demand for plays. Some literati would become fully-fledged playwrights.
Zájù declined and went out of fashion under the dynasties that followed the Yuán; it became especially stultified under the Míng, when all zájù librettos had to pass government censorship. By the time the Míng dynasy fell in 1644, zájù was no longer performed at all and it survived only as a genre of literature, i.e., zájù plays ended up being only read, not played on stage!
A travelling zájù troupe can be the ideal adventurers' party for a TCE campaign game, giving a rationale for travelling from one town to the next and experiencing new encounters. Training for the acrobatics parts of a zájù play is a good cover for martial arts training. The sung arias of a zájù play can be used to convey secret messages to members of the crowd.