3) came to pay their court to the
emperor. Under T'ai-tsung there was national unity and peace, and in
consequence agriculture and commerce as well as literature flourished.
The emperor gave direct encouragements to the Nestorians, and gave a
favourable reception to an embassy from Mahommed (see ante Sec.
_Religion_). On the accession of Kao-tsung (650) his wife, Wu How,
gained supreme influence, and on the death of her husband in 683 she set
aside his lawful successor, Chung-tsung, and took possession of the
throne. This was the first occasion the country was ruled by a dowager
empress. She governed with discretion, and her armies defeated the
Khitan in the north-east and also the Tibetans, who had latterly gained
possession of Kucha, Khotan and Kashgar. On her death, in 705,
Chung-tsung partially left the obscurity in which he had lived during
his mother's reign. But his wife, desiring to play a similar role to
that enjoyed by her mother-in-law, poisoned him and set his son,
Jui-tsung (710), on the throne. This monarch, who was weak and vicious,
was succeeded by Yuen-tsung (713), who introduced reform into the
administration and encouraged literature and learning. The king of
Khokand applied for aid against the Tibetans and Arabs, and Yuen-tsung
sent an army to his succour, but his general was completely defeated.
During the disorder which arose in consequence of the invasion of the
northern provinces by the Khitan, General An Lu-shan, an officer of
Turkish descent, placed himself at the head of a revolt, and having
secured Tung-kwan on the Yellow river, advanced on Chang-an. Thereupon
the emperor fled, and placed his son, Su-tsung (756-762), on the throne.
This sovereign, with the help of the forces of Khotan, Khokand and
Bokhara, of the Uighurs and of some 4000 Arabs sent by the caliph
Mansur, completely defeated An Lu-shan. During the following reigns the
Tibetans made constant incursions into the western provinces of the
empire, and T'ai-tsung (763-780) purchased the assistance of the Turks
against those intruders by giving a Chinese princess as wife to the
khan.

At this epoch the eunuchs of the palace gained an unwonted degree of
power, and several of the subsequent emperors fell victims to their
plots. The T'ang dynasty, which for over a hundred years had governed
firmly and for the good of the nation, began to decline. The history
of the 8th and 9th centuries is for the most part a monotonous record