The Tang empire - the second of the Chinese empires having subcontinental size, after the Han 漢 - stretched from the Tarim Basin 塔里木盆地 to the Korean Peninsula, and from Mongolia down to what is modern Vietnam. The Tang capital was Chang'an 長安 (modern Xi'an 西安/Shaanxi), with the Eastern Capital Luoyang 東都洛陽/Henan, the Northern Capital Taiyuan 北都太原/Shanxi, the Western Capital Fengxiang 西都鳳翔/Shaanxi, the Cental Capital Hezhong 中都河中 (Yongji 永濟/Shanxi), and the Southern Capital Chengdu 南都成都/Sichuan (later Jiangling 江陵/Hubei) as secondary capitals. The whole empire was divided into ten circuits (later more; dao 道; courier type underlined in the map) with subordinated prefectures (zhou 州; in the map abbreviated with the symbol ~; a great part of these designations survives in the name of cities: Yangzhou 揚州, Hangzhou 杭州, Guangzhou 廣州 etc.) and superior prefectures (fu 府, a few areas mostly around the capitals). In the western and southern border regions there were many inferior prefectures headed by submissive chieftains of Non-Chinese tribes (in the map signified by a circle).
The neighboring regions of the Tang empire were administered as protectorate (duhufu 都護府) after the pacification by the Tang armies. There was an eastern, northern, western and southern protectorate (Andong 安東, Anbei 安北, Anxi 安西 and Annan duhufu 安南都護府; the last designation is the origin of the name Annam for northern Vietnam) whose seats changed by time. There existed also a handful of smaller protectorates in the north, like Yanran 燕然, Chanyu 單于, and Beiting 北庭. The citystates of the Tarim Basin along the silkroad became Chinese garrisons, especially the four cities of Yanqi 焉耆, Qiuci 龜茲, Shule 疏勒, and Yutian 于闐. All protectorates were lost during the 9th century. As a subordinated administration unit, submissive chieftains of foreign peoples and tribes were made commander-in-chief (dudu 都督) reigning their territory and people in the name of Tang as area command (dudufu 都督府). This method of bestowing official titles of China to neighboring chieftains makes Tang China much larger as it indeed was.
The Tang Dynasty was heavily shaken in her grounds during the rebellions of An Lushan 安祿山 and Shi Siming 史思明 in the years of 755-759 and 759-763 that originated in the area of modern Beijing but effected the whole northern plain and devastated the capitals Chang'an and Luoyang. From the begin of the 9th century several defense commands - especially in the region north of the Yellow River - rebelled against the Tang government (small yellow dots), in 859-60 Qiu Fu 裘甫 rose up in Zhedong (modern Zhejiang), and in 868-69 Pang Xun 龐勛 in Huainan (modern Jiangsu), but much greater was the rebellion of Wang Xianzhi 王仙芝 and Huang Chao 黃巢 at the lower Yellow River course in the decade 874-884.
The northern neigbors of the Tang empire were Turkish tribes, first the confederation of the Turks (Tujue 突厥) and later singular peoples like the Qarluqs (Geluolu 葛邏祿) and Türgish (Tuqishi 突騎施), and later the new mighty federation of the Uighurs (Huihe 回紇, Huigu 回鶻) that took over the citystates of the Tarim Basin in the 10th century. In the Tibetian highland the empire of Tubo (sometimes read Tufan) developed to a powerful challenger of the Chinese authority. Tubo armies conquered the whole west at the begin of the 9th century. In the southeast hilltribes sometimes said to be ancestors of the modern Thai were untied in the kingdom of Nanzhao 南詔 that occupied modern Yunnan and the north of Laos, Thailand and Burma. In the northeast the Korean kingdom of Silla (Xinluo 新羅) expanded to the north, and in the eastern zone of the Northeastern Plain 東北平原 the kingdom of Parhae (Bohai 渤海) expanded. In the far south the Cambodian kingdom of Zhenla 真臘 had expanded to the north almost to the border of the Tang prefectures.
Annam = Pacified Southern Region (nowadays called northern Vietnam)
Andong = Pacified Eastern Region (nowadays called Liaoning Mandchuria, extended to Korea and Japan)
Anbei = Pacified Northern Region
Anxi = Pacified Western Region (nowadays called Turkestan)