The Legend of the Four Pillars: Tracing the System’s Origins from the Yellow Emperor to the Ming Dynasty

On a crisp autumn morning in 1973, as archaeologists brushed centuries of dust from a lacquered coffin in the tomb complex at Mawangdui, near modern Changsha, they unearthed a silk scroll that would rewrite the timeline of Chinese astrological thought. Dated to 168 BCE, the *Yin-Yang and Five Phases Divination Text* (陰陽五行雜占) contained a fully articulated system of 60 cyclical stems and branches, used to map the rhythms of the cosmos, agricultural cycles, and even human fortune. For scholars of what would later come to be known as Bazi (八字, “Eight Characters”), the find was a thunderclap: the core chronological scaffolding of the system was not a medieval invention, but a tool already in active use over two millennia ago, its roots stretching far deeper than the legendary accounts that had long framed its origin story.

For centuries, the official origin story of Bazi had been rooted not in archaeological evidence, but in the mytho-historical chronicles of China’s earliest dynasties. The *Records of the Grand Historian* (史記) and the later *Book of Later Han* (後漢書) both trace the formalization of the 10 heavenly stems (天干: jiǎ, yǐ, bǐng, dīng, wù, jǐ, gēng, xīn, rén, guǐ) and 12 earthly branches (地支: zǐ, chǒu, yín, mǎo, chén, sì, wǔ, wèi, shēn, yǒu, xǒu, hài) to the reign of the Yellow Emperor (黃帝, c. 2697–2597 BCE), the semi-mythical ruler credited with unifying the warring tribes of the Yellow River valley and laying the foundations of Chinese civilization. The 1st-century CE scholar Ban Gu, in his *Treatise on the Five Elements* (五行志) within the *Book of Han* (漢書), writes explicitly that “the Yellow Emperor created the jiazi (甲子) cyclical system, and used it to order the four seasons, the eight directions, and the twelve months” (黃帝造甲子，以序四時、八方位、十二月)[^1]. This attribution was not mere political propaganda: it tied the nascent system of cosmic chronology to the very origin of Chinese statecraft, framing the measurement of time as a sacred act of aligning human society with the order of the heavens.

The Mawangdui find does not disprove the Yellow Emperor legend, but it does contextualize it: the 60-cycle stem-branch system that forms the backbone of Bazi was already a mature, widely used tool by the early Han dynasty, more than 1,500 years after the Yellow Emperor’s supposed reign. Its formal codification into a state chronological system came in 104 BCE, when Emperor Wu of Han (漢武帝) reformed the calendar to create the Taichu (太初) system, which used the 60-cycle to mark years, months, days, and even two-hour time periods (時辰) that would later form the basis of the four pillars of Bazi[^2]. The Taichu calendar’s integration of stem-branch chronology with astronomical observations of the sun, moon, and five visible planets (Mercury, Venus, Mars, Jupiter, Saturn) cemented the link between cosmic cycles and human timekeeping that would become the core philosophical premise of Bazi: that the rhythms of the heavens are imprinted on the patterns of human life.

For the next 700 years, the stem-branch system was used almost exclusively for chronological record-keeping, agricultural planning, and state ritual. The first evidence of its use to predict individual fortune appears in the 3rd century CE, in the writings of the Daoist alchemist and scholar Ge Hong (葛洪), who in his *Baopuzi* (抱朴子, “Master Who Embraces Simplicity”) notes that some practitioners used a person’s birth year and month to predict their lifespan and fortune, a practice he dismisses as “superstitious trickery” but acknowledges is widespread among the populace. It would take another 500 years for this practice to be systematized into a coherent scholarly framework, a transformation led by the Tang dynasty official Li Xuzhong.

The first figure we can identify with certainty as a practitioner of what would evolve into modern Bazi is Li Xuzhong (李虛中, 762–826 CE), a scholar-official of the mid-Tang dynasty who served as a censor (御史) before retiring to devote himself to the study of cosmic chronology and human fortune. The *New Book of Tang* (新唐書), the official dynastic history compiled in the 11th century, includes a biography of Li in its *Treatise on Fangji* (方技傳, “Biographies of Technical Practitioners”), noting that he “was able to calculate a person’s lifespan, rank, and fortune with perfect accuracy using only the year, month, and day of their birth, matched to the corresponding heavenly stems and earthly branches” (能以人始生年月日所值日辰，支干相生勝衰死生王相，斟酌推人寿夭貴賤，百不失一二)[^3]. Li’s contemporary, the great prose master Han Yu (韓愈), wrote his epitaph, praising his “deep knowledge of the hidden patterns of yin and yang, and his refusal to be misled by the vulgar tricks of fortune-tellers” (精陰陽之術，不為俗術所惑). Han Yu’s account is particularly valuable because it confirms that Li was a respected member of the scholarly elite, not a marginal charlatan: his practice was rooted in the same cosmological frameworks that underpinned Tang dynasty statecraft, not in the superstitious folk practices that later critics would associate with Bazi.

Li’s system, now known as the “three-pillar” (三柱) framework, used only the year, month, and day of birth, omitting the hour pillar that would later become a core part of the system. His calculations relied heavily on the *nayin* (納音) system, a set of 60 paired stem-branch combinations each associated with one of the five phases (wood, fire, earth, metal, water) in a specific state of “birth, prosperity, decline, or death” (長生、冠帶、臨官、帝旺、衰、病、死、墓、絕、胎、養). He also used early versions of the “clash” (沖) and “punishment” (刑) rules that describe the conflicting relationships between certain stem-branch pairs, but did not yet have the formalized “ten gods” (十神) framework that would become central to later Bazi interpretation. A well-documented example of Li’s skill appears in the *New Book of Tang*: he once predicted that the Tang general Wang Bi (王佖), a former Tibetan captive who had defected to the Tang court, would die a violent death in a military conflict in a *you* (酉) year, 11 years after the prediction. Wang Bi was indeed killed in battle in 817 CE, a *you* year, during a campaign against Tibetan forces on the western frontier[^4].

Li’s three-pillar system remained the dominant framework for fortune-telling based on birth time for the next 200 years, but it was in the Song dynasty that the system was transformed into the four-pillar Bazi that remains in use today. The key figure in this transformation was Xu Ziping (徐子平, c. 907–960 CE), a reclusive scholar who lived in the Northern Song capital of Bianjing (modern Kaifeng) and whose name would become synonymous with Bazi for all subsequent generations. Little is known of Xu’s life

The details of Xu Ziping’s life are as elusive as the cosmic patterns he claimed to decode. No official biography of him survives, and the earliest reference to his work appears in the 13th-century *Yuan Hai Zi Ping* (淵海子平, *Comprehensive Collection of Zi Ping’s Principles*), a text that claims to compile his teachings but was likely compiled by his later followers, who sought to formalize his informal, oral instructions into a written system. What is clear from later texts and contemporary anecdotes is that Xu’s work represented a fundamental shift in

The details of Xu Ziping’s life are as elusive as the cosmic patterns he claimed to decode. No official biography of him survives, and the earliest reference to his work appears in the 13th-century *Yuan Hai Zi Ping* (淵海子平, *Comprehensive Collection of Zi Ping’s Principles*), a text that claims to compile his teachings but was likely compiled by his later followers, who sought to formalize his informal, oral instructions into a written system. What is clear from later texts and contemporary anecdotes is that Xu’s work represented a fundamental shift in the system’s purpose: where Li Xuzhong had used three pillars to map broad strokes of fortune and lifespan, Xu expanded the framework to four pillars by ad