How the Yuan reused the Song state

Kublai Khan treated the captured Song ruling house more leniently than many defeated royal families. Emperor Gong was retained as a noble, women of the former royal house were married into Han artisan families, and many Song civil servants continued in government. This relative restraint may have served a practical purpose: destroying or humiliating the old order could damage the administrative system the conquerors wanted to use. Presenting the Song rulers as children unable to govern offered a justification for replacing them while retaining their officials.