The Tang Dynasty of China (618 – 907) had a strong military while it lasted. The military was based on the Fubing system, a local militia system that could be mobilized quickly in times of war. The Fubing system was originated in the Western Wei dynasty of China (535-556), and was adopted by the Tang Dynasty.
The military involved a system of militiamen between the ages of 21 and 60 who were allocated areas of land. Officers were given extended commissions. But regular soldiers reported for duty in the provincial capital on a rotating basis, depending on how far away they lived from the capital. Individuals who lived 500 li (li is half a kilometer) from the capital served one month in five, and those over 2000 li away served for two months out of every eighteen.
In the Tang Dynasty, these military units were under the control of the Ministry of the Army. The Tang Dynasty fielded 634 military units, called Zhechongfu, each consisting of 800 to 1200 men. Each Zhechongfu was divided into sub-units, tuan of 300 men, dui of 50 men, and huo of 10 men.
The Fubing system required only a small amount of government spending, because militiamen could support themselves by farming. The soldiers worked on their land throughout peak farming seasons, and then were given military training during the off-seasons.
The Fubing system could only supply the military for brief campaigns and peacetime. Extended warfare prevented the cultivation of agriculture which the economy depended on. The Fubing system of the Tang Dynasty was gradually abandoned in favor of regular full-time army units in the 8th century.
However, this centralized military system did not last long, and it broke down when many of the fanzhen, or local generals, became increasingly dominant. These fanzhen became so dominant they started collecting taxes, split off and made their own armies, and then made their positions lifetime and family based.
For this reason, the centralized army of the Tang Dynasty was drastically weakened. Eventually, the Tang Dynasty collapsed in the first part of the 9th century as the numerous fanzhen formed separate kingdoms.