It was created by Yuwen Tai 宇文泰 (507-556), the powerful general of the Western Wei dynasty 西魏 (535-556), as a means to ward off attempts of the Eastern Wei 東魏 (534-550) to reunite northern China. In 542, he rearranged the troops of the six frontier garrisons (liuzhenjun 六鎮軍) and various troops of Xianbei 鮮卑 (Taɣbač 拓跋) origin into six armies (liujun 六軍). A year later the Western Wei were badly defeated by the Eastern Wei in the battle of Mangshan 邙山 close to Luoyang 洛陽 (today in Henan). Yuwen Tai had to refill the ranks of his army and therefore ordered the local powerholders to recruit fresh troops and to provide their private armies (buqu 部曲) to the state.
Within a few years, he was thus able to restructure the whole army of the Western Wei empire. It was commanded by eight "Pillars of State" (ba zhuguo 八柱國), twelve Generals-in-chief (da jiangjun 大將軍), and 24 commanders (kaifu 開府) over 24 garrisons. This system imitated the traditional military structure of the Xianbei tribes. Because the highest Pillars of State were the emperor and Yuwen Tai himself, there were in fact only six high commands. The number of garrison troops during that time was about 50,000 men, distributed over 100 garrisons (Zhongguo baike da cidian bianweihui 1990).
The Northern Zhou dynasty 北周 (557-581), heir of the Western Wei, took over this system, but strengthened central control over the garrison troops. The change of its name to shiguan 侍官 "bodyguard" shows that part of the troops were responsible for the protection of the capital. They rotated in service, 15 days being on service to guard the city gates and organizing night patrols, and 15 days off in the garrisons, where they were given military training. The guard troops were responsible to the sovereign, and not any more the Pillars of State. Apart from ethnical Xianbei, many Chinese peasants were registered in the garrison troops, with the promise of being freed from taxes. If only one male member of a house was a soldier (called baiding 白丁), the whole family was registered as a military household (junji 軍籍). Troops lived in garrison compounds (junfang 軍坊), while village troops were organised in township companies (xiangtuan 鄉團). Units of both were commanded by compound heads (fangzhu 坊主) and township company heads (tuanzhu 團主), respectively.
In 590, the Sui dynasty 隋 (581-618) decided to do away with the registration of soldier families in as military households and shifted them back to the farmer registers. The garrison units of the Sui were divided into inner and outer garrisons (neifu 內府, waifu 外府 or neijun 內軍, waijun 外軍). The command of the garrisons was taken over by generals of cavalry (piaoji jiangjun 驃騎將軍) and generals of chariot and horse (cheji jiangjun 車騎將軍), but generals of cavalry sometimes had the command over garrisons of chariot and horse (chiji fu 車騎府), and not just over cavalry garrisons (piaoji fu 驃騎府). Emperor Yang 隋煬帝 (r. 604-617) renamed in 607 all types of garrisons "soaring hawk garrisons" (yingang fu 鷹揚府), and the commanders *soaring hawk commanders (yingyang langjiang 鷹揚郎將) and *stooping hawk commanders (yingji jiangjun 鷹擊郎將).
The imperial bodyguard consisted of three garrisons, namely the *guard of the treasury (siweifu 司衛府), the *guard of nightwatch (siwufu 司武府), and the *military observation guard (wuhoufu 武候府). The Sui divided each of these units in two wings (left and right: zuoweifu 左衛府, youweifu 右衛府, zuo wuwei fu 左武衛府, you wuwei fu 右武衛府, zuo wuhou fu 左武候府, you wuhou fu 右武候府). In 607, Emperor Yang renamed the first two zuo yiwei fu 左翊衛府 and you yiwei fu 右翊衛府 and added further types of units (xiaowei 驍衛, tunwei 屯衛, yuwei 御衛) to a total of 12 guards (wei 衛).
The Tang dynasty did soon away with these names and reintroduced the terms piaoji and cheji. In 636 the outer garrisons were given the official designation assault-resisting garrisons (zhechong fu 折衝府), and their commanders were called assault-resisting commandants (zhezhong duwei 折沖都尉), assisted by left and right courageous commandants (guoyi duwei 果毅都尉). The inner garrisons were renamed commandant garrisons (zhonglangjiang fu 中郎將府). The Tang also changed the names of some of the bodyguard units (tunwei to weiwei 威衛, houwei to jinwuwei 金吾衛), and disbanded the yuwei guard. The total number of units in the "inner garrisons" was sixteen (shiliu wei 十六衛).
|左衛, 右衛||zuowei, youwei||Left and Right Guard|
|左武衛, 右武衛||zuo-you wuwei||Left and Right Militant Guard|
|左金吾衛, 右金吾衛||zuo-you jinwuwei||Left and Right Imperial insignia guard|
|左奉辰衛, 右奉辰衛 (千牛衛)||zuo-you fengchenwei (qianniuwei)||Left and Right Personal Guard|
|左驍衛, 右驍衛||zuo-you xiaowei||Left and Right Courageous Guard|
|左監門衛, 右監門衛||zuo-you jianmenwei||Left and Right Palace Gate Guard|
|左武威衛, 右武威衛 (豹韜衛)||zuo-you wuweiwei (baotao wei)||Left and Right Militant and Awesome Guard (Guard of Leopard Strategy)|
|左戎衛, 右戎衛 (玉鈐衛, 領軍衛)||zuo-you rongwei (yuqianwei, lingjunwei)||Left and Right Martial Guard (Guard of Jade Strategy, Metropolitan Guard)|
There was also the guard command (shuaifu 率府) which protected the Eastern Palace (Donggong 東宮), during the Tang called left and right defense guard (zuo-you weishuai 左右衛率), left and right protective guard command (zuo-you siyushuai 左右司御率), and left and right police patrol guard command (zuo-you qingdaoshuai 左右清道率), together Six Commands of the Eastern Palace (Donggong liu shuai 東宮六率). The commanders of all these units were called commandants (zhonglangjiang 中郎將), supported by left and right assistant commandants (zuo-you langjiang 左右郎將). The inner guards as a whole were divided into three units, called bodyguard garrisons (qinfu 親府), distinguished garrisons (xunfu 勳府), and standby garrisons (yifu 翊府), and the soldiers accordingly bodyguard (qinwei 親衛), distinguished guardsmen (xunwei 勳衛), and standby guardsmen (yiwei 翊衛), together the "three guardsmen" (sanwei 三衛). The units were commanded by left and right commandants (zuo-you wei 左右衛) and left and right defense guard commandants (weishuai 衛率).
The staff of the inner garrisons had official rank 2 to 5, and their posts were hereditary, which means that sons, grandsons or younger brothers automatically succeeded into vacancies. The rank of outer garrison troops ranged down to 8, and positions were filled according to the principle that wealthy families with many sons were first, while poor families or such with only one son would not be forced to provide their son to the army. The great number of common troops therefore hailed from the peasant population, while positions of officers were occupied by men from wealthy families.
Because service in the rank and file was obligatory and families freed from tax paying, the troops served for a period of just three years and were then exchanged. Emperor Xuanzong 唐玄宗 (r. 712-755) extended the service period to six years. The military recruited men of the age between 21 and 59 sui. Even if the families were freed from corvée obligations and tax payment, weapons and equipment as well as travel expenses were not provided by the government. The only thing the government took over were six horses or mules (beasts of burden, tama 馱馬) for the transport of the equipment of ten men (called one huo 火).
The "outer garrisons" did normally not allow soldiers to leave the place of service. In peacetime, they worked as farmers and so contributed to the self-subsistence of the garrisons, yet at the same time trained for military service. Small units of five were transferred to the capital, where they took turns in monthly service (fan 番) as guards. Those located farther away from the capital(s) served for longer periods in order to save the way. Troops of garrisons located between 100 and 500 li 里 (see weights and measures) away from the capital served five periods (wu fan 五番, 5 months), those located between 500 and 1000 li for 7 months, those located between 1000 and 2000 li for eight rounds (8 months), and those more than 2000 li away for a very long double-period of 9 fan 九番 (18 months!).
Troops of the inner garrisons and those of garrisons located very close to the capitals Chang'an 長安 (today's Xi'an 西安, Shaanxi) and Luoyang did not serve, but were instead cut part of their salaries. The protection of the capitals was their duty anyway. Troops serving in the capital guard were usually commanded by the commanders of their home garrison, but when campaigning, they obeyed to the command of a general appointed by the central government. This general was given a "fish tally" (yufu 魚符) by the Ministry of War (bubing 兵部) which was to be counter-checked by regional inspectors (cishi 刺史) and the commanders of the assault-resisting garrisons (zhechong fu 折沖府) before he could set the troops into march. When a campaign was over, the troops returned into their garrisons, and the general to the court. In this way, it was avoided that a general would march against the capital, backed by the loyalty of his "own" troops.
The total number of garrison troops during the Tang period changed over time. The highest number of garrisons was about 633 (Yang and Zhang 1992). The fubing garrisons were scattered over the country, but most of them were located in the circuit (dao 道) of Guannei 關內, i.e. Shaanxi, namely 261 garrisons. Less heavy concentrations of garrisons were found in Hedong, Henan, Hebei, and Longyou (Gansu), while circuits in southern China were only protected by a few garrisons.
Apart from the garrison troops, the Tang dynasty also knew other types of troops, namely the Palace Guard (jinjun 禁軍, liujun 六軍, beiyajun 北衙軍) whose garrison was located directly north of Chang'an. For local defense and during military campaigns, ad-hoc units recruited troops from among the populace. In the later half of the Tang dynasty, local milita units (tuanjiebing 團結兵, shizhenbing 士鎮兵) became common. The number of ad-hoc recruits often surpassed that of the garrison troops, but their fighting power was naturally much lower than that of the professionals.
In the mid-8th century the system of temporary recruitment and rotation service became unfeasible. The main reason were the many military conflicts emerging during that period, which made it necessary to extend the service periods longer and longer. Desertion therefore became commonplace. A second reason was the increasing contempt of the social elite towards the profession of soldiers. In the early Tang, military virtues were still highly admired, but the growing cultivation of civilian and scholarly virtues changed this situation. The third reason for the decline of the fubing military system was that it relied on the recruitment of free peasants. Yet in the course of time, the nobility appropriated more and more land, the so-called zhuangyuan estates 莊園, so that the amount of free peasants declined and that of tenant farmers increased. The latter were not liable for taxation and could therefore not be recruited for military service. The situation was so bad that there were not troops enough to fill the ranks of the capital guard.
Counsellor-in-chief Zhang Yue 張說 (663-730) therefore suggested in 722 to create a new type of army with voluntary recruits instead of drafted ones. The project began in the prefectures around the capital. In 725 the system was called guoqi 彍騎. It fully replaced the former system of guard units. In 737, Emperor Xuanzong ordered the local military commissioners (jiedushi 節度使) to replace the garrison system with a recruitment system in which "strongmen" (jian'er 健兒) were to fill the ranks of the army. At first the court did not set a limit to the number of recruits in case of war, but a year later issued the decree to disband superfluous troops. Yet it allowed the creation of huge standing armies in the prefectures which were not any more dispatched for service in the capital, and therefore became more or less "private" armies of the local commanders. Moreover, the use of "fish tallies" was given up, and thus an important instrument of curtailing the power of generals abolished.
Even if the garrisons were void of troops, the titles of officers remained in use even after the fall of the Tang.