Map of the Tang Dynasty

This map covers the years from 754 (the 13th year of Tianbao), the year before An Lushan rose in revolt, to 906 (the 3rd year of Tianyou), the year before the Tang fell. For every year it records who held each prefecture at the end of the year, taken from the histories, and draws each power's territory from that. Move the year to watch the borders shift; click a prefecture to see who held it, year by year.

The coloured powers are the Tang; the states that took the Tang capital and claimed the title of emperor — Yan (An Lushan and Shi Siming), Qin (Zhu Ci) and Qi (Huang Chao); Chu (Li Xilie), which claimed it at Bianzhou; and the Tibetan Empire, Nanzhao and the Uyghurs. The Khitan, the Xi, Balhae, the Tanguts, the Kyrgyz and others appear only as names at the edges of the map.

The red square marks the city where an emperor or king was at the end of the year. In years when the Tang emperor spent the end of the year away from the capital, Chang'an, it is placed where he was: Ningzhou (Pengyuan) in 756, Fengtian in 783 and Xingyuan in 880, for example.

The military provinces (fanzhen, governed by military governors) are shown in three ways. Provinces that obeyed the court keep the Tang colour. Provinces whose governors the court could not appoint, and which passed from father to son or to a subordinate — the three Hebei provinces (Chengde, Weibo and Lulong), Ziqing, Huaixi and others — are drawn as separate areas in the Tang colour with the province's name (a prefecture's history marks them “nominal”). In years when the court ordered a campaign against a province, or its governor called himself king or emperor, it is grey, outside the Tang. The warlords who fought over the prefectures in the late Tang (Zhu Quanzhong, Li Keyong, Yang Xingmi, Wang Jian and others) are also drawn in the Tang colour with their names for as long as they held Tang offices.

The “greatest extent of the Tang” often seen in textbooks and online is a map of the 660s, under Gaozong, that counts nominal prefectures (jimi prefectures) from Central Asia to the Mongolian steppe. This map starts in 754, the year before the An Lushan Rebellion, and does not draw nominal prefectures, so its western and northern edges look different. Here the western edge of the Tang in 754 is the Four Garrisons of Anxi (Qiuci, Yutian, Shule and Yanqi) and Beiting.

Click the gear at the bottom right of the map and turn on “Show modern cities” to see provincial capitals and other cities of today. Type a modern name such as “Nanjing” into “Find by modern name” under the same gear to open the prefecture at that place.

Years follow the year divisions of the Zizhi Tongjian. Events of the twelfth month count in that year, though by the modern calendar they may fall in January or February of the next (the twelfth month of the first year of Guangming, when Huang Chao proclaimed himself emperor in Chang'an, was January 881 by the modern calendar).

For 237 major prefectures, we took from the histories who held the prefecture's city at the end of each year, and attached the source passage to every change of hands. The main source is the Zizhi Tongjian, checked against the Old and New Books of Tang (the basic annals, the treatises on geography and the biographies), with the Old and New Histories of the Five Dynasties and the Shiguo Chunqiu for the late Tang: 1,723 passages in all, each machine-checked to appear word for word in the text, and for the Zizhi Tongjian to appear under the heading of that year. Sieges and occupations given up within the year do not change a prefecture's holder (as when the Arabs and Persians burned Guangzhou and left in 758, or when Huang Chao took Guangzhou and went north again in 879).

The borders are inferred by machine from who held the prefectures. The land is divided into 4 km squares, and each square is given to the power whose prefecture can be reached from it with the least effort, allowing for steep mountains and the difficulty of crossing great rivers. Land far from every prefecture (steppe, desert, plateau, the uplands of non-Han peoples) is left uncoloured and fades out. Liangzhou, Ganzhou and Suzhou in Hexi are coloured as widely as other prefectures; Guazhou, Shazhou, Yizhou, Xizhou and Beiting to the west are oasis cities in the desert and are coloured a little more narrowly. The Four Garrisons of Anxi (Qiuci, Yutian, Shule and Yanqi) lie hundreds of kilometres apart, so a wider area is coloured around each, so that the rim of the Tarim Basin reads as one stretch of Tang land.

Where the prefectures of one power lie apart and its colour breaks off, they are joined by a band along a route that does not cross another power's land (up to about 400 km on level ground). A prefecture surrounded by another power's land (an exclave) is drawn as a circle about 36 km in radius.

Borders at the time were zones rather than lines, and the lines on this map show only roughly where those zones lay.