employment, as were the glass and metalworking industries. Imports stimulated new regional centres of production. Southern Gaul became a leading producer of the finer red-gloss pottery (terra sigillata) that was a major item of trade in 1st-century Europe. Glassblowing was regarded by the Romans as originating in Syria in the 1st century BC, and by the 3rd century, Egypt and the Rhineland had become noted for fine glass. Performing arts In Roman tradition, borrowed from the Greeks, literary theatre was performed by all-male troupes that used face masks with exaggerated facial expressions that allowed audiences to "see" how a character was feeling. Such masks were occasionally also specific to a particular role, and an actor could then play multiple roles merely by switching masks. Female roles were played by men in drag (travesti). Roman literary theatre tradition is particularly well represented in Latin literature by the tragedies of Seneca. The circumstances under which Seneca's tragedies were performed are however unclear; scholarly conjectures range from minimally staged readings to full production pageants. More popular than literary theatre was the genre-defying mimus theatre, which featured scripted scenarios with free improvization, risqué language and jokes, sex scenes, action sequences, and political satire, along with dance numbers, juggling, acrobatics, tightrope walking, striptease, and dancing bears. Unlike literary theatre, mimus was played without masks, and encouraged stylistic realism in acting. Female roles were performed by women, not by men. Mimus was related to the genre called pantomimus, an early form of story ballet that contained no spoken dialogue. Pantomimus combined expressive dancing, instrumental music and a sung libretto, often mythological, that could be either tragic or comic. Although sometimes regarded as foreign elements in Roman culture, music and dance had existed in Rome from earliest times. Music was customary at funerals, and the tibia (Greek aulos), a woodwind instrument, was played at sacrifices to ward off ill influences. Song (carmen) was an integral part of almost every social occasion. The Carmen saeculare of Horace, commissioned by Augustus, was performed publicly in 17 BC by a mixed children's choir. Music was thought to reflect the orderliness of the cosmos, and was associated particularly with mathematics and knowledge. Various woodwinds and "brass" instruments were played, as were stringed instruments such as the cithara, and percussion. The cornu, a long tubular metal wind instrument that curved around the musician's body, was used for military signals and on parade.