16 Chapter Onewere far-reaching. Steppe populations, once they had mastered the
arts of horsemanship and acquired the skills to make bows, arrows,
and all necessary accoutrements from materials available to them lo
cally, had a cheaper and more mobile armed force at their command
than civilized peoples could easily put into the field. Steppe warriors
could therefore raid civilized lands lying to the south of them almost
with impunity, unless rulers were able to replicate barbarian levels of
mobility and morale within their own armed establishments.
Setting a thief to catch a thief was one obvious tactic. This was, in
fact, what Xerxes and his Achaemenid predecessors resorted to for
the protection of their exposed frontier upon the steppe. Most
Chinese rulers did the same. By paying tribesmen to defend the bor
der against would-be raiders, an impervious membrane could be
stretched along the frontier. But this sort of arrangement was always
liable to break down. Border guards were continually tempted to join
forces with those outer barbarians whom they were paid to oppose,
since in the short run plunder was likely to bring richer returns than
they could ever hope to achieve by renegotiating rates of pay with
governmental authorities.
Within this general framework, endlessly variable military, diplo
matic, and economic relationships between steppe tribesmen and
civilized rulers and bureaucrats ensued across the next two thousand
years. Protection payments alternated with raids; occasionally de
structive plundering impoverished all concerned. The rise and fall of
steppe war confederations around individual captains, who were often
charismatic leaders like the greatest of them, Genghis Khan (1162—
1227), introduced another variable. But despite endless perturbations
of the political and military relationships between grassland and
plowland, peoples of the steppe enjoyed a consistent advantage be
cause of their superior mobility and the cheapness of their military
equipment. This produced a pattern of recurrent nomad conquests of
civilized lands.
Whenever local defenses weakened, for whatever reason, nomad
raiding could be expected to snowball year by year, as news of suc
cessful plundering expeditions spread across the steppe. If local de
fenses crumbled completely, raiders were tempted to remain perma
nently in occupation of the lands that had been unable to protect
themselves. Thereupon, of course, raiders became rulers and soon
recognized the advantage to themselves of substituting taxation for
plunder and of protecting their taxpaying subjects from rival preda
tors. Under these conditions, locally effective defense might be ex-