When  the  Han  Dynasty  ended  in  221  A.  D.,  Yu  Chou  was
handed  about  from  kingdom  to  kingdom  and  was  for  some  200
years  under  the  control  of  the  tartars.  The  city  survived  this
"Period  of  Darkness,"  however, >nd  when  China  was  once  more
united  under  the  Sui  and  T'ang  Dynasties,  Yu  Chou  served  as
the  residence  of  a  military  governor.
Yu  Chou  again  came  under  the  control  of  the  barbarians
when,  during  the  first  half  of  the  Tenth  Century,  a  Chinese
Emperor  ceded  sixteen  districts  to  the  Khitans  in  gratitude  for
their  help  in  placing  him  upon  the  throne.  Later,  under  the  Sung
Emperors,  the  Chinese  attempted  to  regain  these  lost  districts
but  were  only  partially  successful.  Their  armies  came  as  far  as
the  Kao  Liang  River,  which  is  now  the  canal  from  the  new  Sum-
mer Palace  to  the  moat  around  the  walls  of  Peking,  but  failed  in
their  attempt  to  capture  the  city.  The  Chinese  were  badly  de-
feated and  the  Sung  Emperor  was  forced  to  flee  for  his  life.
Later  attempts  to  regain  this  territory  were  even  less  successful
and  soon  the  army  of  the  Khitans  invaded  the  territory  of  the
Sungs  and  forced  them  to  pay  tribute  to  the  emperors  of  the
north.
