Beating with the light stick (chi 笞) was a common means of corporal punishment (see also penal tools) in ancient China and belonged to the five capital punishments (wuxing 五刑). It was carried out by beating with bamboo sticks (zhuban 竹板) or bundles of rods of the thornbush (jing 荊, vitex) on the back or the back part of the legs of a delinquent. The law code Tanglü shuyi 唐律疏議 saw the pentaly as a means to humiliate (chi 恥; a homophone to 笞) and to castigate with the aim to "educate" (xun 訓). The penalty is mentioned in the law codes of the Qin period 秦 (221-206 BCE, see Qin Bamboo Texts), and was used more extensively after Emperor Wen 漢文帝 (r. 180-157 BCE) of the Han dynasty 漢 (206 BCE-220 CE) commuted the traditional mutilations (rouxing 肉刑) into blows with thorn rods. Cutting off the nose (yi 劓), for instance, was commuted into 300 blows with the thorn rod bundle, and cutting off the left foot (fei 剕) into 500. Nevertheless, this "less severe" kind of punishment was still so harsh that persons usually died before the process was finished.
Emperor Jing 漢景帝 (r. 157-141 BCE) therefore reduced the number of strokes to 300 and 200, respectively, and shortly after to 200 and 100. In the "Flog statute" (Chui ling 箠令), the thorn rod bundle was replaced by a bamboo stick. It was 5-chi 尺 long and 1-cun 寸 wide (see weights an measures), but converging at the end to half a cun. The nodes of the bamboo were rasped away to obtain a smooth surface. The stick was flogged on the buttocks (men) or on the back (women), and the punishment carried out in one go.
The term chi was from the Sui period 隋 (581-618) on also used for one type of the heavy stick (zhang 杖). Legal texts are thus sometimes unclear about these two penalties. Blows with the stick were regularly applied in addition to other penalties, like exile (liu 流) or penal servitude (tu 徒), or were used in combination with lashes by the whip (bian 鞭). The Northern Zhou dynasty 北周 (557-581), for instance, decreed that exile was punished in addition with 100 lashes with the whip, and between 60 and 100 blows with the light bamboo, depending on the distance of exile.
The Sui dynasty commuted lashes with the whip into blows with the bamboo altogether. From then on, beating with the light stick was the lowest in the canon of the five capital punishments. It was also allowed to commute the 10, 20, 30, 40 or 50 blows by payment of money (shuzui 贖罪). The Tang dynasty 唐 (618-907) followed this precedent, but developed more detailed rules. The thornbush rod bundle (then called chu 楚) was reintroduced, and the law courts discerned between the "light stick" (chi 笞) with a small head (xiaotou 小頭) of 1.5 fen 分 of width, and the "heavy stick" (zhang 杖) with a large head (datou 大頭) 2 fen wide. There was a difference of punishment between beating on the legs and beating on the buttocks.
The Song dynasty 宋 (960-1279) introduced the possible commutions of blows with the light stick (chi, on the back or the legs) by a lower number blows with the heavy stick (zhang) on the buttocks. 50 blows with the light stick were commutably by 10 blows on the buttocks with the heavy stick, 30 or 40 blows with the light stick by 8 with the heavy stick, and 10 or 20 with the light stick by 7 with the heavy one.
The Liao dynasty 遼 (907-1125) did not know the bamboo as a punishing instrument, but instead applied blows with a wooden sword (mujian 木劍) or a great stick (dabang 大棒) on the back. The penal system of the Jin dynasty 金 (1115-1234) made use of blows with willow twig bundles (liutiao 柳條). The large-head version of the stick from the Yuan period 元 (1279-1368) was 2.7-fen thick, that with the small head 1.7 fen. Blows on the buttocks were applied in six possible grades with quite peculiar numbers of 7, 17, 27, 37, 47, and 57 blows.
The sticks used by the Ming dynasty 明 (1368-1644), made of smoothened rod bundles of the thornbush, were 3.5-chi 尺 long. While size of the large head was 2.7 fen, that of the small head 1.7 fen. These sticks were usually beaten on the legs, but the Qing dynasty 清 (1644-1911) allowed commutation into blows with the heavy stick on the buttocks. The Kangxi Emperor 康熙帝 (r. 1661-1722) ordered the optional commutation of 10 blows with the light bamboo stick by 4 blows with the heavy stick, that of 20-odd with the light one by 5 with the heavy one, that of 30-odd with the light one by 10 with the heavy one, 40-odd with the light one by 15 with the heavy one, and 50 blows with the light bamboo by 20 with the heavy one. The thornbush rod bundle, used until then as the "light" version of the stick, was again replaced by a bamboo stick with a length of 5.5 chi. The width of the large head of the light bamboo was 1.5 cun, that of the small head 1 cun. The weight should not surpass 1.5 jin 斤.