In spite of his long rule, Wu Ti did not leave an adult heir, as the
crown prince was executed, with many other persons, shortly before Wu
Ti's death. The crown prince had been implicated in an alleged attempt
by a large group of people to remove the emperor by various sorts of
magic. It is difficult to determine today what lay behind this affair;
probably it was a struggle between two cliques of the gentry. Thus a
regency council had to be set up for the young heir to the throne; it
included a member of a Hsiung-nu tribe. The actual government was in the
hands of a general and his clique until the death of the heir to the
throne, and at the beginning of his successor's reign.

At this time came the end of the Hsiung-nu empire--a foreign event of
the utmost importance. As a result of the continual disastrous wars
against the Chinese, in which not only many men but, especially, large
quantities of cattle fell into Chinese hands, the livelihood of the
Hsiung-nu was seriously threatened; their troubles were increased by
plagues and by unusually severe winters. To these troubles were added
political difficulties, including unsettled questions in regard to the
succession to the throne. The result of all this was that the Hsiung-nu
could no longer offer effective military resistance to the Chinese.
There were a number of _shan-yü_ ruling contemporaneously as rivals, and
one of them had to yield to the Chinese in 58 B.C.; in 51 he came as a
vassal to the Chinese court. The collapse of the Hsiung-nu empire was
complete. After 58 B.C. the Chinese were freed from all danger from that
quarter and were able, for a time, to impose their authority in Central
Asia.

5 _Impoverishment. Cliques. End of the Dynasty_