Pei Ju
In the realm of cartography, there were further advances beyond the map-makers of the Han dynasty. When the Tang chancellor Pei Ju (547-627) was working for the Sui dynasty as a Commercial Commissioner in 605, he created a well-known gridded map with a graduated scale in the tradition of Pei Xiu (224-271). The Tang chancellor Xu Jingzong (592-672) was also known for his map of China drawn in the year 658. In the year 785 the Emperor Dezong had the geographer and cartographer Jia Dan (730-805) complete a map of China and her former colonies in Central Asia. Upon its completion in 801, the map was 9.1 m (30 ft) in length and 10 m (33 ft) in height, mapped out on a grid scale of one inch equaling one hundred "li" (Chinese unit of measuring distance). A Chinese map of 1137 is similar in complexity to the one made by Jia Dan, carved on a stone stele with a grid scale of 100 li. However, the only type of map that has survived from the Tang period are star charts. Despite this, the earliest extant terrain maps of China come from the ancient State of Qin; maps from the 4th century BC that were excavated in 1986.