What does it mean to send the frontier to compete all over the south of the Yangtze River?

Refers to criminals sentenced to banishment or exile and escorted by officers. Border, territory close to national boundaries; Remote places. Sending criminals to the Jiangnan frontier means that criminals are sentenced to exile or exile and escorted by officials. Border, territory close to national boundaries; In remote areas, people who can't get out of this frontier without any means of transportation can only do coolies in that desolate place. This life is worse than death.