Various forms of media portray Sun Wukong wearing three types of golden headbands (jingu, 金箍; a.k.a. jingu, 緊箍, lit: “tight fillet”). The first has blunt ends that meet in the middle of the forehead and curl upwards like a pair of scowling eyebrows. The second has an upturned crescent moon shape in the center. And the third is just a thin fillet devoid of any adornment (fig. 1). This article will briefly discuss the origins of type two, what I call the “crescent-style” headband.
Fig. 1 – Type 1 (left): Curlicue. From the comedy A Chinese Odyssey Part Two: Cinderella (1995); Type 2 (center): Crescent. From the famous 1986 CCTV series; and Type 3 (right): Thin band. From the 2011 TV show (larger version).
I. Ties to the stage
The type two headband is heavily associated with Liu Xiao Ling Tong‘s (六小齡童; a.k.a. Zhang Jinlai, 章金萊, b. 1959) portrayal of the Monkey King from the famed 1986 CCTV series. This actor comes from a long line of Chinese opera performers who specialize in playing Sun Wukong. It should be no surprise then that the type of circlet that he wears comes directly from Chinese opera. Known as a “precepts headband” (jiegu, 戒箍), this fillet is worn on stage by Military Monks (wuseng, 武僧) as a sign that they’ve taken a vow of abstinence (Bonds, 2008, pp. 177-178 and 328). Such clerics are depicted as wearing a jiegu in combination with a wild mane of hair (fig. 2), which contrasts with the bald heads of religious monks.
II. Appearance in zaju theater
To my knowledge, the oldest source associating Sun with the precepts headband is an early-Ming zaju play that predates the standard 1592 edition of Journey to the West. In act ten, the Bodhisattva Guanyin tells Monkey:
Great Sage Reaching Heaven [a previous title for Sun], you originally destroyed form and extinguished nature, but the honored monk saved you. This time, you will cease your desires. I give you the dharma name Sun Wukong, as well as an iron precepts headband [tie jiegu, 鐵戒箍], a black monk’s robe, and a precepts knife.  The iron headband will guard your nature, the robe will cover your beastly body, and the knife will cut your relations. If you want to go with your master, then you will be called Pilgrim Sun. Swiftly obtain the scriptures and seek the right fruit.
The precepts headband likely finds its origin in the triple-crescent crown of Central Asia. This crown was originally a fixture of Iranic Hephthalite royalty that was later adopted by Sogdian rulers. Zoroastrian gods were even portrayed wearing it. The motif is known to have entered China as early as the 6th-century. For instance, the stone tomb of the Sogdian leader Di Caoming (翟曹明, d. 579) features two foreign-looking, trident-wielding door guardians wearing the crown (fig. 3 & 4). Most importantly, a crown featuring the triple-crescent and wings (also of Hephthalite origin) appears in Chinese Buddhist art, particularly in the headdresses of Bodhisattvas (fig. 5), before, during, and after the Tang and Liang periods (Kageyama, 2007). Therefore, the association of the triple-crescent with guardians and Buddhist deities might then explain why it was later connected to military monks in Chinese opera.
Fig. 3 – Triple-crescent crown-wearing guardians on the door of Di Caoming’s stone tomb (larger version). Fig. 4 – A detail of one of the guardians (larger version). Images found on this tweet. Fig. 5 – A diagram showing the various Bodhisattva crowns featuring the triple-crescent and winged adornments in Chinese Buddhist art (larger version). From Kageyama, 2007, p. 22. 
I’m indebted to the art historian Jin Xu (徐津) for posting a tweet about Sino-Sogdian funerary art, which led to him explaining the origin of the precepts headband.  I’m also indebted to Eran ud Turan for directing me to a lovely paper on the triple-crescent and winged crowns.
IV. Many influences
This subject is fascinating as it shows how different cultures came to influence the Monkey King’s headband. The general concept of a circlet serving as a physical reminder of right speech and action comes from India, and it was associated with gods in Esoteric Buddhism. The curlicue-style fillet is likely based on Chinese representations of stylized lingzhi (靈芝) mushrooms, which were associated with Daoist deities. And lastly, the crescent-style band is based on the crown of two Iranic cultures, and it was associated with divine beings from Zoroastrianism.
Various forms of media portray the Monkey King wearing different kinds of headbands. The second type, which includes an upturned crescent moon shape in the middle of the forehead, is featured in Chinese opera depictions of Sun Wukong. This “precepts headband” (jiegu, 戒箍) is a symbol of military monks, thus linking Monkey to such martial clerics. To my knowledge, the oldest source associating our hero with the jiegu is an early-Ming zaju play in which Guanyin gives Sun an “iron precepts headband” (tie jiegu, 鐵戒箍) (among other items).
This style of circlet was likely influenced by the “triple-crescent crown” used by the Iranic Hephthalite and Sogdian cultures as a symbol of royalty. The motif appeared in China as early as the 6th-century as evidenced by the stone tomb of Di Caoming, which features foreign-looking door guardians wearing the triple-crescent crown. Most importantly, the motif also adorns the crowns of Bodhisattvas during China’s medieval period, which (combined with the aforementioned door guardians) might explain why the crescent came to be associated with military monks in Chinese opera.
This Iranic crown is one of three cultural threads influencing the function and look of Monkey’s golden headband, the other two coming from India (Esoteric Buddhism) and China (Daoism).
1) Precept knives (jiedao, 戒刀) were historically small, unadorned, curved, finger-length blades used for cutting robes, trimming fingernails, opening wounds, or slicing food (Yifa, 2009, p. 250, n. 37).
2) The diagram is labeled thusly in the original paper:
Winged crowns and triple-crescent crowns represented in the Buddhist art of the Northern and Southern Dynasties and the Sui. a, c, e-h: Wall paintings. Dunhuang (Gansu). a: Cave 254 (Northern Wei. Second half of the fifth century or first half of the sixth century), c: Cave 285 (Western Wei. 538-539 CE), e: Cave 276 (Sui. Late sixth or early seventh century), f. Cave 380 (Sui. Late sixth or early seventh century), g. Cave 389 (Sui. Late sixth or early seventh century), h. Cave 407 (Sui. Late sixth or early seventh century). b: Stone sculpture from Wanfo-si 万仏寺. Liang. First half of the sixth century. Chengdu (Sichuan). d. Stone relief from Dazhusheng 大住聖 Cave, Baoshan Lingquan-si 宝山霊泉寺, Anyang. Sui. 589 CE (Kageyama, 2007, p. 22).
3) After asking him a question on the original tweet, Jin Xu replied:
This type of crown is the prototype of Jiegu. It was a headgear favored by Sogdians, as you can see in some pictures taken by @eranudturan. I’m not sure if it had a specific name at the time, but perhaps related to later Persian word “taj” (tweet).
Bonds, A. B. (2008). Beijing Opera Costumes: The Visual Communication of Character and Culture. Honolulu: University of Hawai’i Press.
Kageyama, E. (2007). The Winged Crown and the Triple-crescent Crown in the Sogdian Funerary Monuments from China: Their Relation to the Hephthalite Occupation of Central Asia. Journal of Inner Asian Art and Archaeology, 2, 11-22. Retrieved from https://isaw.nyu.edu/publications/jiaaa/Kageyama.pdf.
Yifa. (2009). The Origins of Buddhist Monastic Codes in China: An Annotated Translation and Study of the Chanyuan Qinggui. Honolulu: University of Hawai’i press.