The last performing-arts genre to develop in Central Asia was the Buddhist morality play, called a-che-lha-mo. The plays are based on the lives of legendary and historical figures, and through costume and masks the ethnic origin and ethical character of the players are revealed. Folktales, as well as historical and Buddhist canonical literature, are sources for the stories presented in a-che-lha-mo. Most plays are about mythical heroes who prove that Buddhism and its virtues conquer all evil in the end; but there are those that tell the story of historical personages.

Although traditions among the Central Asian peoples are vague about the development of shamanic rituals and ’cham, they are clear about the origin of a-che-lha-mo and even point out the historical creators of the art. Some scholars regard the plays as derivatives of Indian theatre, but Tibetan tradition claims that the first performance of a morality play was produced by Thang-stong rgyal-po, a famous bridge builder of the 15th century.

One story tells of some Tibetans who were building a bridge and found that whatever they assembled during the day, demons dismantled at night. Thang-stong rgyal-po, a holy man well versed in the capricious ways of demons, advised the Tibetans to stage a play to divert the attention of the evil spirits. By this stratagem, they were able to complete the bridge. This story would seem to indicate that the primary purpose of the play was to entertain, but another story illustrates that Thang-stong rgyal-po realized that religious teachings would have a greater influence on the people if they were dramatized, so he developed the morality play to serve this purpose. Regardless of his intent, a-che-lha-mo evolved as didactic entertainment, and Thang-stong rgyal-po is regarded by the Tibetans as its patron saint.

From primitive beginnings, the morality plays developed into a popular performing art, complete with stylized costumes and masks, complex scenarios and effective staging. The scripts are written in a dialogue song style called rnam-thar. There are at least nine traditional plays in the Tibetan repertoire.

The most common type of a-che-lha-mo is the drama based on legend and mythology which often reflects a strong influence of Indian theatrical tradition. An example is the play ’Das-log Snang-sa. The phrase ’das-log means to return (log) from the beyond (’das) and is used in Tibetan to refer to anyone who was believed to be dead and then returns to life and relates all that was witnessed in the netherworld. ’Das-log Snang-sa is about a virtuous woman named Snang-sa who was unjustly accused of adultery and beaten to death by her jealous sister-in-law. When Snang-sa was led before the fierce Lord of the Dead (gshin-rje), he found that she was pure of heart and mind, and he allowed her therefore to return to life. Once home again, however, her husband and relatives began to mistreat her, so she became a nun. The play ends with Snang-sa flying away from the convent roof and disappearing like a rainbow in the sky.

Another type of a-che-lha-mo is the plays based on the lives of Tibetan holy men or pious kings. Rgya-bza’ Bal-bza’ (“Chinese-wife, Nepalese-wife”), for example, tells the story of king Srong-btsan sgam-po (died 649 ce) and his two Buddhist wives—Wen-ch’eng, a Chinese princess, and Bhrikuti, a princess from Nepal. These three historical figures are believed by faithful Tibetans to have been incarnations of Buddhist deities, and their story is very popular with the audience.

The performance of a play may take more than a day. Narrative recitation is used to set scenes, delineate character, and give continuity to the songs that tell the main story. Comic sketches or dances are performed between the acts. Each character in a play has a distinctive costume or mask. Usually Tibetan male characters and the heroes wear no mask, while virtuous female characters wear flat, teardrop-shaped masks, particularly the serpentine deities. Three-dimensional masks are worn by evil foreigners, demons, and witches, and masks that cover the entire head are used to portray animals. Like the ’cham, the morality play is performed outdoors, with the audience, except for the specially seated lamas and nobles, standing or sitting on the ground around the performing area.

The morality plays are performed for profit by groups consisting of lay men and women, and some have Buddhist monks or nuns as members. These troupes are generally associated with a given locale, such as a village or a monastery; however, they often travel to give performances on special occasions, transporting their wardrobe and stage props with them. In time, four of the most popular troupes were required by the Tibetan government to perform plays at the summer palace of the Dalai Lama. These performances were obligatory as a kind of taxation. There are still several of the a-che-lha-mo troupes to be found among the Tibetan refugees in Nepal and India, where their performances are in popular demand.

The a-che-lha-mo did not spread from Tibet into other parts of Central Asia until the 19th century. According to tradition, the Mongolian lama Noyan Hutuqtu (1803–56) studied a-che-lha-mo as performed in the Kokonor (Tsinghai) region of northeastern Tibet and then introduced his own adaptations of it at Tulgatu-yin keyid, his own monastery near the village of Saynshand, in Mongolia. For the first time, in 1832, he produced a repertoire of four plays, and their performance required 17 full days. The four plays were based on the textual biographies of the historical Buddha, the Indian Buddhist Teacher Atīśa, the revered Tibetan hermit-poet Mi-la Ras-pa, and the fabulous “Moon-cuckoo” (Saran-u Kökügen-ü Namtar), a mystical story of a pious prince who became a cuckoo bird living in the forest.

Noyan Hutuqtu’s productions differed from the usual performance of a-che-lha-mo in certain respects. His repertoire did not include any of the plays traditional in Tibet. His actors, unlike those of a-che-lha-mo, wore no masks; instead, they painted their faces, a makeup technique associated with Chinese opera. Whereas a-che-lha-mo is usually performed outdoors in the Himalayan regions, Noyan Hutuqtu had a special theatre constructed near his monastery. It was a three-sided, two-storied, mud-brick building with two stage floors; thus, two scenes could be performed at the same time. The upper stage represented the sky, the lower one the earth. There were stage exits on both sides and trap doors in the floor.

The first Mongolian actors were called schabi, or disciples, of the lama Noyan Hutuqtu. These men and women formed a regular troupe and were invited all over Mongolia to perform.