Who suggested sending letters to raise people to migrate to Xiaxia?

It was Chao Cuo who suggested sending a letter to raise people to emigrate.

In the 11th year of Emperor Wendi (BC 169), Emperor Wendi adopted Chao Cuo's suggestion and sent a letter to recruit people to immigrate to Xia Sai. On the issue of resisting Xiongnu's invasion of the border, he put forward the strategic idea of "migrating to the real border", and suggested that the people should be nurtured to enrich the frontier fortress and actively prepare for Xiongnu's attack and plunder.

Politically, it is suggested to cut down governors and deprive them of political privileges to consolidate centralization, which harms the interests of governors. In the name of "Please punish Chao Cuo to be clean", transfer troops to rebel. Jingdi listened to Yuan Ang's plan and beheaded Chao Cuo in the East City.

Immigrant solid edge:

Eleven years before Wendi (BC 169), Chao Cuo gave Wendi a book "On Military Affairs". Put forward the viewpoint of "controlling foreigners with foreigners". Chao Cuo did not advocate relying solely on barbarians, but tried to combine with China's army, so that "the two armies were both outward and inward, each with its own skills", and advocated taking the initiative to attack the Huns, which was politely rejected by Emperor Wen.

Then he put forward the strategy of active defense to Wendi, that is, "guarding the border to persuade farmers to cherish" and "recruiting people to cherish" In "Guarding the Border and Encouraging Agriculture", Chao Cuo analyzed the mistakes of the Qin Dynasty's policy of guarding the border and the characteristics of the Huns' national activities. Put forward the viewpoint of "immigrant reality". Chao Cuo's idea of "emigrating to the real border" is an active defense, which was adopted by Emperor Wen.

In order to better recruit immigrants, Chao Cuo put forward two suggestions in "Realistic Recruitment of Immigrants": First, he put forward specific measures to resettle immigrants' lives. Second, we should learn from ancient methods and organize immigrants in strict accordance with the military organizational system.

At the same time, Chao Cuo suggested in "On Your Millet Sparrow" that the people of the whole country send grain to the frontier fortress in exchange for a title or atonement. This is called the title Su Na. These measures advocated or decided by Chao Cuo laid an important material foundation for the economic development and "the rule of culture and scenery" in the early Han Dynasty.