People are curious about the iron coupon of Dan Shu because it has the so-called "death-free" effect. In fact, this kind of thing didn't have this function when the Emperor Gaozu Liu Bang first created it, as can be seen from Han Xin's extermination of the three clans and Xiao He's imprisonment. Because at that time, it was just a certificate of promotion and knighthood. To say that it really has the effect of "avoiding death", in the Northern and Southern Dynasties, people who owned it could avoid death once or three times, but only for themselves.
During the Northern Wei Dynasty, Emperor Xiaowen often issued iron coupons to clan relatives and trusted ministers, and even some ministers begged the emperor for iron coupons. In the Sui and Tang Dynasties, he gradually began to use golden crossword puzzles instead of scarlet crossword puzzles, which is also the origin of the "gold medal for avoiding death". At that time, it was almost a rule that the founding heroes were given iron coupons, and the effect of avoiding death was gradually improved. From the beginning 1-3 times to avoid death, become yourself 9 times, and future generations can avoid death 3 times. As the saying goes, "... you forgave the deaths of nine people and three children." Or make routine punishment, a department shall not add responsibility ... "It can be said to be a veritable" golden book iron coupon ". In the Ming Dynasty, in order to strengthen the norms and prevent forgery, iron coupons were usually divided into two parts, one for the transferee and the other for the imperial court to consult. At this time, there will no longer be so many opportunities for death-free cards, and future generations will no longer enjoy this right.
It was not until the Qing Dynasty that this kind of iron coupon of Dan Shu was really abolished.