Reunified Empires 53
weakness of the Sui court. A northern nomadic tribe that had been a
Sui ally before the Korean invasions now turned against Sui forces and
nearly captured the emperor himself in 615. Civil war soon erupted
as many Sui commanders saw no more advantage in following orders
from a monarch so prone to hopeless wars as Sui Yangdi.
In 617, Li Yuan, one of the major military commanders in north
China (and a fi rst cousin of Sui Yangdi), led his troops in revolt against
the Sui, quickly capturing the capital city of Chang’an. Within six
months of his initial act of rebellion, Li Yuan proclaimed a new dynasty,
the Tang, and moved quickly against several rival armies in the north.
His forces captured the secondary Sui capital of Luoyang in 621 and
took the major cities of the Yangzi River valley by 624. In 626, Li Yuan’s
ambitious son Li Shimin imprisoned his father, killed two of his broth-
ers, including the heir apparent, and seized the throne himself, taking
the title Tang Taizong. By 628, all remnants of internal resistance to
the Tang forces were eliminated, but Tang Taizong still had to contend
with powerful nomads, the Khitans, and Eastern Turks on the northern
and northwestern borders of the empire. Through a combination of
military successes and strategic alliances with the Turks, Tang Taizong
won for himself the title Great Khan, thus facilitating the joint Chinese-
Turkish pacifi cation of the Central Asian cities and oasis towns of the
Silk Roads, extending Tang hegemony as far west as Kabul, Kashgar,
and Samarkand by the mid-seventh century.
Tang Taizong ruled from 626 to 649. He succeeded where Sui Yangdi
failed, in establishing his dynastic rule over a greater area than the Han
had enjoyed and in putting the new dynasty on a fi rm foundation. Much
like the Han before it, the Tang maintained the institutions put in place
by their predecessors and used them more fl exibly and effectively. To
curb the power of the aristocratic families of the south, the Sui rulers had
forced leading southern families to move to the capital city of Chang’an
in the north. The Sui had instituted a new “rule of avoidance” (con-
tinued by the Tang), which stipulated that no offi cial could serve the
government in his own home district. This effectively ensured that local
elites could not use their government positions to the advantage of their
own families. The equal-fi eld system, fi rst implemented by the Wei in
the north and by the Sui in the south, was also maintained by the Tang.
And the Tang court mobilized and maintained the same two kinds of
armies used by the Sui—both self-supporting soldier-farmers who served
as militiamen in times of need and full-time professional soldiers.
Tang Taizong was ruthless in his seizure of the throne, but he was
also a shrewd judge of character in appointing competent and loyal