The tuntian 屯田, literally "scion fields", were agro-colonies, mostly in border regions, that served to supply the inhabitants and Chinese colonists with agricultural products. Some of these colonies were of purely civilian character (mintun 民屯, yingtian 營田), but most of them were staffed with military personnel (juntun 軍屯). In fact, also many civilian agro-colonies served to supply military garrisons with grain.

The first of these colonies were created under the reign of Emperor Wu 漢武帝 (r. 141-87 BCE) of the Han dynasty 漢 (206 BCE-220 CE), when large amounts of troops in the newly conquered territories in the west (the Western Region 西域) had to be provided with grain and other foodstuff. In times of disunity, like the Three Kingdoms period 三國 (220-280), the Southern and Northern Dynasties period 南北朝 (300~600) or during the Song period 宋 (960-1279, between the Song and the Liao 遼, 907-1125, and Jin 金, 1115-1234, empires), border troops garrisoned in the zone of the Huai River region (modern Anhui and Jiangsu, north) were supplied with the help of tuntian created in this region, during the Three Kingdoms period also in the border region between the Wei 曹魏 (220-265) and Shu 蜀漢 (221-263) empires (between modern Shaanxi and Sichuan), and during the last phase of the Northern Dynasties period 北朝 (386-581) also in northern China between the contending states Western Wei 西魏 (535-556) and Eastern Wei 東魏 (534-550) and their successor states Northern Zhou 北周 (557-581) and Northern Qi 北齊 (550-577).

A rather small amount of military colonies was created in the heart of the imperial states and not in border zones. This was the case under the Eastern Han 東漢 (25-220 CE), the Cao-Wei dynasty 曹魏, the Northern Wei 北魏 (386-534) and the Tang dynasty 唐 (618-907). This greatly changed under the conquest dynasties Liao (Khitans 契丹), Jin (Jurchens 女真) and Yuan 元 (1279-1368, Mongols 蒙古) that supplied their occupation troops throughout all regions with the help of agro-colonies.

In 196 CE the warlord Cao Cao 曹操 transferred the seat of the emperor, Xiandi 漢獻帝 (r. 189-220), to his own residence in Xu 許 (today's Xuchang 許昌, Henan). In order to supply this provisional capital and the guard troops with food, he ordered to found agro-colonies in the surroundings. This measure was quite effective, so Cao Cao decided to spread the system throughout the territory he controlled. The results were felt soon. Not only was Cao Cao able to feed his troops in the fight against contending warlords like Yuan Shao 袁紹 or Yuan Shu 袁術, but he also reconstructed the economy of north China, where shortly before the rebellion of the Yellow Turbans (huangjin 黃巾) had devastated the countryside. After all the agro-colonies were a cornerstone of the Wei empire founded in 220 CE. The workforce on the agro-colonies close to Xu came to a substantial part from young persons formerly fighting for the Yellow Turbans in the province of Qingzhou 青州 (approx. today's Shandong). He had transferred whole households over hundreds of miles, including kettle and agricultural tools, and resettled around Xu. Another group of peasants employed in the agro-colonies were "floating people" (liumin 流民), farmers who had lost their fields or wandered around, escaped war, turmoils and famine.

The peasants working the fields of the agro-colonies were called tuntian ke 屯田客 or diannong bumin 典農部民. The fields and the peasant households working on them were not administered by the district authorities, but by specifically appointed officials, so-called *agricultural governors (diannong zhonglangjiang 典農中郎將 or diannong xiaowei 典農校尉) and *agricultural magistrates (diannong duwei 典農都尉). The agro-colonies of the whole empire were subordinated to the Chamberlain for the National Treasury (dasinong 大司農). The basic territorial unit of the colonies were "sprouts" (tun 屯), overseen by commanders (sima 司馬), and managed by fifty peasants. The military character of the agro-colonies can not only be seen in the names of officials administering them, but also in the fact that the peasants were subordinated to military law, as if they were soldiers. Yet apart from these "civil colonies" (mintun 民屯), there were also military colonies (juntun 軍屯).

The officials administering these military colonies were called *tax governors (duzhi zhonglangjiang 度支中郎將 or duzhi xiaowei 度支校尉) and *tax magistrates (duzhi duwei 度支都尉), but were likewise subordinated to the Chamberlain for the National Treasury. The basic unit was the garrison (ying 營) with about 60 persons. It might have been that there was a difference between border colonies (shibing tuntian 士兵屯田) and inland colonies (shijia tuntian 士家屯田), the former populated by soldiers, and the latter by persons being farmers in peacetime and soldiers when campaigns were planned. The fields of the colonies were owned by the government. Peasants hiring "state-owned" draft animals delivered sixty per cent of the harvest to the government, those using their own oxen, half. While household members of the military colonies had to deliver corvée labour (see yaoyi 徭役), this was not required from the household of the civil colonies. The largest military agro-colony of the Wei empire was located along the River Huai 淮水 (what is today northern Anhui and Jiangsu) and owned a workforce of up to 100,000 people.

Even after the foundation of the Wei empire agro-colonies served to support the economy. Only in 264 the emperor decided to transform the territories into regular commanderies (jun 郡) and districts (xian 縣), yet it seems that the transformation was not fully accomplished: In 266, under the newly founded Jin dynasty 晉 (265-420), it was once more ordered to abolish the agro-colonies.

The Ming dynasty 明 (1368-1644) inherited the Mongol system of the military households (junhu 軍戶), in which posts were inheritable. In peacetime the troops of the garrisons (weisuo 衛所) made their lives as peasants, and in war times served as soldiers. This had also been the case in the early Han period agro-colonies. The Ming period garrisons (wei 衛) had a quota size of 5,600 troops (and their families and "households"), battalions (qianhusuo 千戶所) 1,120 households, and companies (baihusuo 百戶所) 112. The problem of feeding the border garrisons in the north was at that time solved in a different way. Merchants were commissioned to transport grain to the border garrisons and were provided in turn with salt vouchers (yanyin 鹽引) that allowed them to monopolized the trade in salt throughout the empire. A small number of colonies were called merchant colonies (shangtun 商屯) because they served to produce the grain in the border zones that otherwise would have to be transported over long distances from grain-producing provinces. The Manchus, founders of the Qing dynasty 清 (1644-1911), created a throughly new military system (the Banners and the Green Standards) and supplied their troops with a salary instead of with grain. Military agro-colonies were only founded in the border regions of Mongolia, Tibet, Eastern Turkestan and southwest China. A quite small number of agro-colonies to supply the transport (caoyun tuntian 漕運屯田).

The number of agro-colonies greatly changed over time. It can be estimated that during the Han period there were about 600,000 troops living in the colonies in the west. During the Tang period the colonies in the northeast and northwest covered about 50,000 qing (1 qing corresponding to about 6 or 7 hectares) of land, while those of the Song period only had a size of 4,200 qing. Yuan agro-colonies throughout the empire had a size of at least 180,000 qing, and that of the Ming period 640,000 qing.

The labourers of the military agro-colonies were provided with tools, beasts, and seeds. Any surplus of grain yields surpassing the need of the garrison was handed over to the authorities. In the Wei empire households using government-owned oxen handed over sixty per cent of the harvest, while those using private animals were allowed to keep fifty per cent. These rates were drastically reduced during the Western Jin period 西晉 (265-316) and in the Former Yan empire 前燕 (337-370): Those lending out government animals handed over eighty per cent, and those possessing their own draught animals handed over seventy per cent of the harvest to the government.

The size of the northwestern colony land was 65 mu per household, with a rent of 26 shi (1 shi corresponding to 26.4 kg during the Han) of grain, which makes for 4 shi per mu. Under the Northern Wei and the Southern Dynasties the male heads of the households were to pay 60 hu of grain per mu. During the Ming and Qing periods each household was given 50 mu of land the yields of which were to be used for the labourers working for the transport of tribute grain along the Grand Canal. In the region of Liaodong the rent was 15 shi (1 shi corresponding to 70.8 kg during the Ming) per field in the beginning, but later reduced to 12 shi, but the same amount was to be delivered to the authorities to supply the garrison. Later on the rent was reduced to 6 shi. In the region of Ili 伊犁, occupied under the Qing dynasty, the amount of grain to deliver to the authorities was 13 shi (1 shi corresponding to 71.6 kg during the Qing) per year.

The creation of the agro-colonies in borderlands and in remote territory substantially contributed to the economic development of wasteland and wilderness. The colonists opened new fields and created irrigation channels. Their supply of the border garrisons with grain made the occupation of territories possible that were located far away from the political centre of the empire. The colonization of southwest China by civilians that worked the fields of the colonies was an important step for the integration of backwards provinces into the unfied empire of the Ming and Qing dynasties. On the other side, many colonists were forcibly settled down in the borderlands and often tried everything to travel back to their homelands.