It was very fixed because the base was formed of self sufficient economy in the medieval society. The local administrative system had been managed with the regional origin of family genealogy, Bongwan(本貫), especially in Goryeo Dynasty. Bongwan was important to all the officials, soldiers, merchants, farmers and etc.
Nevertheless there were many varieties of moving out. Among the rest the migration of the officials was remarkable in records. The local group in each district usually entered government service. They had to succeed in Gwageo(科擧), the state examination to recruit ranking officials, and to move to Gaegyeong(開京). Though they sometimes lost their official posts, they could not move out. Contrary to the officials, the common people had to leave Bongwan to get living. So they could keep away from various kinds of tax burden, famine and infectious disease.
There were differences in the settlers in Gaegyeong by their origins, who were government officials, local group and former military men. Some were wealthy and the others were barely enough. But wondering people left for new land to cultivate. The government framed the polices to take the trouble for the settlers.