(一)汉武帝时候,汉跟匈奴展开了三次大战,打败了匈奴,夺取了河套和河西走廊。西汉帝国的势力一直达到西域。为了巩固边防和有效地控制这些地区,西汉帝国必须派出大量的军队去戍守边疆。要把大量的军需给养输送列遥远辽阔的边疆去,是人民一项非常沉重的徭役,也是国家一项非常巨大的负担。汉政府就命令戍兵就地选择水草丰美的地方,“通沟渠,种五谷”,自己来解决军粮的给养。后来,赵充国上了一个“屯田十二便”的奏章,以后,就把戍兵垦殖叫作:“屯田”。元鼎六年(公元前111年),“初置张掖、酒泉(按系敦煌之误)郡。而上郡、朔方、西河、河西开田官,斥塞卒六十万人戍田之。(原注:开田,始开屯田也。)”(汉书卷24下食货志)这是西北边疆屯田的开始。汉跟西域的交通畅通以后,“西域……多遣使来贡献,汉使西域者益得职。于是自敦煌西至盐泽,往往起亭,而轮台渠(?)皆有田卒数百人,置使者校尉领护,以给使外国者。(原注:收其所种五谷以 (A) Han Emperor, Han and the Huns launched three wars, defeated the Huns, captured the Loop and the Hexi Corridor. The Western Han Empire forces have reached the Western Regions. In order to consolidate the frontier defense and effectively control these areas, the Western Han Empire must send a large army to guard the frontier. It is a very heavy battle for the people to transport a large amount of military supplies to the vast and remote border areas and is also a huge national burden. The Han government ordered garrisons to choose the places where the plants are plentiful and the “ditches and grain growing” were used to solve the problem of providing food for themselves. Later, Zhao Chongguo went to a memorial called “Twelve Potato Wastes,” and later called Garrison Cultivation “Tuentian.” Yuan Ding six years (111 BC), “the initial Zhangye, Jiuquan (according to the Department of Dunhuang mistakes) County, while the county, Shuofang, Xihe, Hexi Kaneda officer, condolences to slash six hundred thousand people field. The original note: open fields, began to open up the farmland too.) ”(Han volume 24 under cargo) This is the beginning of the Northwest Frontier Tuntian. After the smooth flow of traffic between the Han and the Western Regions, "the Western Regions ... made an extra contribution to make the beneficiaries of the Western Regions benefit from their posts. People, set the messenger Lieutenant leadership to give foreigners