
Dae-gil had begged his father to allow him to marry Un-nyun, saying that he couldn't live without her. Furious, his father had ordered that Un-nyun be locked up in the storage room, where she would be left to die from dehydration.
Slaves who ran away were rounded up by bounty hunters called chuno-kkun. “Chuno” itself is a portmanteau word combining “chase” with “slave”; hence, slave hunter.
In the Manchu war, amidst the chaos and fighting, invaders had raided homes and dragged off their inhabitants.
Chun Ji-Ho is nothing if not an opportunist. He tells his men to fire away. If he manages to kill Dae-Gil and the runaway slave, that's like killing two birds with a few dozen arrows.