The T'ang literature shows the co-operation of many favourable factors. The ancient Chinese classical style of official reports and decrees which the Toba had already revived, now led to the clear prose style of the essayists, of whom Han Yü (768-825) and Liu Tsung-yüan (747-796) call for special mention. But entirely new forms of sentences make their appearance in prose writing, with new pictures and similes brought from India through the medium of the Buddhist translations. Poetry was also enriched by the simple songs that spread in the north under Turkish influence, and by southern influences. The great poets of the T'ang period adopted the rules of form laid down by the poetic art of the south in the fifth century; but while at that time the writing of poetry was a learned pastime, precious and formalistic, the T'ang poets brought to it genuine feeling. Widespread fame came to Li T'ai-po (701-762) and Tu Fu (712-770); in China two poets almost equal to these two in popularity were Po Chü-i (772-846) and Yüan Chen (779-831), who in their works kept as close as possible to the vernacular. New forms of poetry rarely made their appearance in the T'ang period, but the existing forms were brought to the highest perfection. Not until the very end of the T'ang period did there appear the form of a "free" versification, with lines of no fixed length. This form came from the indigenous folk-songs of south-western China, and was spread through the agency of the _filles de joie_ in the tea-houses. Before long it became the custom to string such songs together in a continuous series--the first step towards opera. For these song sequences were sung by way of accompaniment to the theatrical productions. The Chinese theatre had developed from two sources--from religious games, bullfights and wrestling, among Turkish and Mongol peoples, which developed into dancing displays; and from sacrificial games of South Chinese origin. Thus the Chinese theatre, with its union with music, should rather be called opera, although it offers a sort of pantomimic show. What amounted to a court conservatoire trained actors and musicians as early as in the T'ang period for this court opera. These actors and musicians were selected from the best-looking "commoners", but they soon tended to become a special caste with a legal status just below that of "burghers".