Who was the first to discuss and systematically expound the theory of "immigrant reality" in history?

When Chao Cuo, the minister of the Western Han Dynasty, put forward the policy proposal of "moving people to the real border" to Emperor Wendi, he clearly pointed out that an important prerequisite for the success of "moving people to the real border" is to ensure that immigrants can take root in the frontier for a long time: "I heard that since ancient times, immigrants have always been based on reality, can taste their springs, judge their land, observe their vegetation and be kind, and then build cities."