A jùn (郡) was a historical administrative division of China from the Eastern Zhou (c. 7th century BCE) until the early Tang dynasty (c. 7th century CE). It is usually translated as a commandery. Countries around China have adopted administrative divisions based on or named after the jùn. History and development China Eastern Zhou During the Eastern Zhou's Spring and Autumn period from the 8th to 5th centuries BCE, the larger and more powerful of the Zhou's vassal states—including Qin, Jin and Wei—began annexing their smaller rivals. These new lands were not part of their original fiefs and were instead organized into counties (xiàn). Eventually, jun were developed as marchlands between the major realms. Despite having smaller populations and ranking lower on the official hierarchies, the jun were larger and boasted greater military strength than the counties. As each state's territory gradually took shape in the 5th- to 3rd-century BCE Warring States period, the jun at the borders flourished. This gave rise to a two-tier administrative system, with counties subordinate to jun. Each of the states' territories was by now comparatively larger, hence there was no need for the military might of a jun in the inner regions where counties were established. The border jun's military and strategic significance became more important than those of counties. Qin dynasty Following the unification of China in 221 BCE under the Qin Empire, the Qin government still had to engage in military activity because there were rebels from among the six former states who were unwilling to submit to Qin rule. As a result, the First Emperor set up 36 jun in the Qin Empire, each subdivided into counties. This established the first two-tier administrative system known to exist in China. Han dynasty and Three Kingdoms period When the Han dynasty triumphed over Chu in 206 BCE, the Zhou feudal system was initially reinstated, with Emperor Gao recognizing nearly independent kings and granting large territories to his relatives. These two sets of kingdoms were placed under hereditary rulers assisted by a chancellor (xiàng). Parallel to these, some Qin jun were continued, placed under a governor appointed directly by the central government. By the Eastern Han dynasty, the jun were subordinated to a new division, the province (zhōu). — establishing a three-tier system composed of provinces (zhou), commanderies (jun), and counties (xian). Based upon legendary accounts of the Yellow Emperor's Nine Provinces which were