What four cities do "Hexi four counties" refer to? Which city is the "Pearl on the Hexi Corridor"?

In the early years of the Western Han Dynasty, the agricultural areas under the jurisdiction of the Western Han government were often harassed by Xiongnu and Xiqiang in the north and west of the Great Wall, killing and injuring border people, looting property, destroying agricultural production and plundering border people as slaves. After Emperor Wu of the Han Dynasty ascended the throne, in order to make peace with the country and fight against Xiongnu, Zhang Qian and Gan Fu (ethnic minorities) were forced to communicate with the western regions, intending to unite with the people. At this time, because the Yue family had established a country in the summer, they didn't want to go back to their hometown in the East to be enemies with the Xiongnu, so the purpose of uniting the Yue family was not achieved. After Zhang Qian's second mission to the Western Regions, he gradually achieved the goal of uniting Wusun and the agricultural countries south of Tianshan Mountain to fight against Xiongnu.

In the Han Dynasty, a large agricultural area was established in the north of the Great Wall, which was cultivated by settlers. In BC 12 1 year, the Huns king Xie Kun and king Xiutu, who lived in Hexi area, surrendered to the Han Dynasty. In the Han Dynasty, Kun Xie was named as the source of Yin Hou, and four of his subordinates were named as Liehou. More than 40,000 people from its Ministry were placed in Longxi, Beidi, Shang Jun, Shuofang and Yun Yun, which were called the five quasi-countries. According to History of Han Geography, in BC 104, the Western Han government established Jiuquan County and Zhangye County, in1kloc-0/year, Wuwei County, and in 88, Dunhuang County. According to the historical records of Emperor Wu of the Han Dynasty, in the second year of Yuanshou (before 12 1), the evil king fell, and his place was Wuwei and Jiuquan County. Ding Yuan for six years (former 1 1 1) was divided into Zhangye and Dunhuang counties. It is more reliable to refer to relevant historical materials. According to the Records of Hanshu Geography, the number of registered permanent residence in Hexi four counties is as follows:

Name, family, population, county, plain and river basin.

Dunhuang 1 1200 38355 6 Shule River in Dunhuang Plain

Jiuquan 18 137 76726 9 Heihe River is in Jiuquan Plain.

Wuwei175817641910 Shiyang River in Yongchang Plain.

Zhangye 24352 8873 1 10 Heihe River in Zhangye Plain

Total 7 1270 28023 1 35

There are more than 70,000 households with more than 280,000 people, most of whom are Han immigrants. 12 1 years ago, "the evil king of Han Naizi set Jiuquan County as his hometown and moved some people to be rich." 1 1 1 years ago, "Wucheng and Jiuquan were divided into Zhangye and Dunhuang counties, and immigrants took them for themselves. /kloc-before 0/07, "Wudu rebelled and moved to Jiuquan. Before "102", there were 60,000 people who pardoned prisoners, became delinquents, rode on the edge and left Dunhuang at leisure. " "Easy to die in180,000 Jiuquan, Zhang. Settle in Juyan and retreat to Jiuquan. Before "9 1", he sent troops with Wang Wei ... all the officials and scholars moved to Dunhuang County. "

There are three pearls in Hexi Corridor: Wuwei City, Zhangye City and Jiuquan City.