By AD 589, when Yang Chien established himself at the head of a newly reformed Chinese empire, nearly four centuries had elapsed since the fall of the last great imperial dynasty: the Han. Although Yang's new Sui regime consciously modelled itself on its great predecessor, both China and the world outside had changed. The problem for the Sui and their successors was no longer simply to 'overawe the barbarians', but to deal as equals with other cultures that were just as proud and self-confident as their own. Chris Peers examines the imperial armies of China from 590-1260 AD, covering their history, organisation and tactics.