Han refers to the territories ruled by lords.
Han in Japan
Han in terms of Japanese history is a historical term that refers to the territories ruled by daimyo (Japanese feudal lords) who possessed a domain of 10,000 or more goku crop yields in the Edo period and the governance structure. Han derives from the Chinese name of a Chinese system to which Japanese Confucian scholars in the Edo period compared Japanese system.
Because the term Han was not the official name of a system in the Edo period, only some people used it, and it occasionally appeared after Genroku era (e.g. Hakuseki ARAI's books "Hankanpu" [Genealogy of the Protectors of the Shogunate] and "Tokugawa jikki" [The True Tokugawa Records].)
Han became a public name in the Meiji period, and then it came into widespread use.
Originally, the term 'Han' referred to the territories ruled by the lords who were allowed to govern a certain country by the emperors of the Zhou Dynasty, ancient China, and the Japanese Confucian scholars in the Edo period compared the Japanese system to this, calling the daimyo who were (thought to be) subject to the TOGUGAWA Shogun family and given the territories by the shogun 'Shoko,' and their domains 'Han.'
In the Edo period, the term 'Han' was a nickname in Confucian literature so that it was not used in official systems and other names, such as 'XX kachu (family),' were used instead.
In modern historical terms, the daimyo who were feudal lords of Han are called 'Hanshu', and the daimyo's vassals were called 'Hanshi.'
In addition, direct control territories of the bakufu (Japanese feudal government headed by a shogun) are called 'Tenryo' in modern historical terms in comparison to Han, and Daikan (local governor) or Gundai (intendant of a region or administrator of a town) collected land taxes there.
However, for instance, retainers of the governor in Mutsu Province were rarely called 'Sendai Hanshi' in the Edo period, and they were officially called 'Matsudaira Mutsu no kami no Kerai' (retainers of the governor of Mutsu Province) (the Date family was given the cognomen of 'Matsudaira' by the shogun family.)
In addition, many daimyo families preferred to call themselves 'Soshi' rather than 'Hanshi', both were of Chinese origin.
In many cases, daimyo were called by their domain names with 'Ko' (lord), rather than 'Hanshu.'
For example, 'Sendai Ko,' 'Owari Ko,' and 'Himeji Ko'.
Certain self-sustained politics, economy and society were well organized inside Han within a framework of the authority of the seii taishogun (literally, "great general who subdues the barbarians") and the Edo bakufu, so the inside of Han functioned like a small country.
Han started when shugo daimyo (Japanese territorial lords) dismantled manors and employed local lords-grade samurai who had owned a territory in each farming village and the village headmen who had become local samurai as their vassals, firmly building a system to rule the whole region in their territory. It was a new control pattern that was different from the samurai's control over their territory before the Muromachi period. While the Sengoku daimyo further pushed to rule the whole region in their territory, they started to gather their vassals, samurai, in their castle town and bring the samurai under their tight control. Nobunaga ODA continuously moved the samurai's territories that Nobunaga exacted according to their power and progress, and Hideyoshi TOYOTOMI made the Sengoku daimyo that Hideyoshi subjugated, including Ieyasu TOKUGAWA, move in their entirety from their base territory to a new fief. Therefore, the separation of the occupations and social ranks between samurai and peasants progressed in the Azuchi-Momoyama period, and it was completed by the Battle of Sekigahara and by actively adding or changing Daidaimyo's (a feudal lord having a greater stipend) territories in the early Edo period.
The typical pattern of Han was to have samurai, Hanshi, in the castle town as military men or government officials who collected land taxes in rice from peasants whose yields were registered in villages located in the whole ruling region in the vicinity of the castle town, and divided the taxes into the financial resources for the Han and Hanshu as well as the salaries for the Hanshi. However, among small domains newly organized by the Tokugawa clan, some had separate territories which lay astride other domains and ruling the whole region was difficult for them.
When the new Meiji government regionalized the former territories of the bakufu into prefectures called Fu or Ken as the direct control territories of the emperor (tenryo) in 1868, 'Han' was newly adopted as an official name for the daimyo's domains because the daimyo's domains were thought to be the emperor's 'Han', so 'XX Han' became the official way of calling administrative divisions, with the 'XX' for the Hanshu's location (or castle, if daimyo had one) (fu-han-ken sanchisei [fu-han-ken tripartite governance system].)
By the following year, 1869, daimyo returned their lands and people to the emperor and their title was changed from Hanshu to Chihanji (governor,) and based on the Haihan-chiken (the abolition of feudal domains and establishment of prefectures) in 1871, Han were replaced with prefectures. Consequently, the fief system since the Edo period was abolished, and the lands of the domains were consolidated.
In 1872, a year after the Satsuma Domain, the practical ruler of Ryukyu, became Ken by the Haihan-chiken, Ryukyu was changed from an independent kingdom to the Ryukyu Domain which belonged to Japan. From then to the Ryukyu Annexation in 1879, Ryukyo was the only area to stay under the fief system in Japan after the Haihan-chiken.
Today's prefectures were formed by integrating the prefectures at the time of the Haihan-chiken, but in the cases of large scale domains which had social status of landed daimyo, their territories are rarely identical with those of today's prefectures.
Han in China
It is said that the term Han derives from the fact that the lords who guarded the royal family were called 'Han' in ancient China during the Zhou dynasty. Later, Han came to refer to the lords and their territories, whose country was in a vassal relationship with the Chinese empire. The territories were also called Hankoku (a.k.a. Bankoku).
The term Han was used from the Han dynasty to the Qing Dynasty, but it was rarely used to form a proper noun like ' XX Han' in Japan.
Hanchin was the name used to call jiedushi forces (a regional military governor) who ruled their own territories in regional areas from the late Tang Dynasty to the Wudai Shiguo period.
The Three Han that were remote semi-independent states in the Qing Dynasty are well-known.
Han in India and Pakistan
For details, refer to the chapter titled 'Hanokoku.'