After conquering the Shang, King Wu spared the royal descendants of the defeated dynasty and enfeoffed Wu Geng, son of King Zhou of Shang, as ruler of Zhaoge (present-day Qi County, Henan), allowing the Shang royal line to continue. To keep the former Shang territory under control, King Wu appointed three trusted younger brothers — Shu Xian of Guan, Shu Du of Cai and Shu Chu of Huo — as the "Three Guards" to monitor Wu Geng. Shu Du earned distinguished merits in the campaign against Shang and held high rank.

Three years later, King Wu passed away, and his young son Ji Song ascended the throne as King Cheng of Zhou. Since the new emperor was still a minor, Zhou Gong Dan, another brother of King Wu, stepped forward to govern the state as regent. This triggered fierce opposition. While some nobles backed the regent, Shu Du of Cai, Shu Xian of Guan and Shu Chu of Huo accused Zhou Gong Dan of usurpation. They issued proclamations across the realm, calling on feudal lords and court officials to launch a punitive expedition against him. Wu Geng immediately raised troops to join the uprising. The conflict became known as the Rebellion of the Three Guards, throwing the newly founded Zhou Dynasty into chaos.

Acting in the young king’s name, Zhou Gong Dan launched an eastern campaign. Backed by royal authority, his army secured a decisive victory. Shu Xian of Guan and Wu Geng were executed; Shu Chu of Huo was demoted to commoner status. Shu Du of Cai was arrested and imprisoned near Chanhu Temple (later known as Guolin), 2.5 kilometres northwest of today’s Shangcai County seat, and his fief was revoked. He died of grief and indignation in 1038 BC.

The war between Zhou Gong Dan and the State of Cai was fought mainly around the capital city. Built on a mound, the city was encircled by the Ruhe River and crisscrossed by brooks, making it impassable for chariots. Shu Du once defended the city relying on these water barriers. Zhou Gong’s troops seized the Chanhu Temple area first and then breached the northern city wall, leading to the fall of the capital. A stele from the Qing Dynasty at Chanhu Temple records: "Zhou Gong marched east, stationed his troops on Luling Ridge, and captured the city only after a prolonged siege."

History written by the victors branded Shu Du a rebel. Modern local historians hold a more sympathetic view, commenting: "Zhou Gong ought to have consulted the feudal lords before assuming the regency. Shu Du’s suspicion of usurpation was understandable. If the city had been fully fortified back then, the outcome might have been different." It is only natural that the defeated Shu Du ended up with a tarnished reputation.

A man of strong character, Shu Du wasted away in captivity. His son Hu led a virtuous and mild life, breaking away from his father’s course. Zhou Gong Dan recommended Hu to serve as a senior official in the State of Lu, where he assisted Boqin in governing the state efficiently. In 1038 BC, Zhou Gong petitioned King Cheng to restore Hu to the fief of Cai. Hu became the second ruler, historically remembered as Zhong of Cai.

After returning to Cai, Zhong of Cai set up state institutions and resumed his father’s unfinished project of city construction. A model administrator, he was prudent, hard-working and lived alongside common folk, often wearing linen clothes and straw sandals and labouring together with villagers. He personally took part in designing and building the city wall. Thanks to collective efforts, the rampart was finished within just two years.

Three millennia later, local archaeologists explain the ancient construction techniques on site: "You can still trace the old moat outside the wall. Workers dug the moat and piled up the rammed earth simultaneously. The moat was completed as soon as the wall stood. In Western Zhou city-building, the plank ramming method was adopted: wooden planks formed a frame, earth was filled inside, then compacted with rammers. After one layer solidified, the planks were raised higher for the next stratum, layer by layer."

Standing on the ancient site, we can almost hear the rhythmic heave of labourers ramming earth three thousand years ago. Exploring the ruins of this ancient city calls for not only observation but also imagination.

The palace district stood at Erlang Platform south of present-day Wangzhuang Village in the centre of the city. This raised ground covers 1.2 million square metres, rising six to seven metres above the surrounding land. The Chronicle of Shangcai County records: "Wangzhuang, in the northwest of the city, was traditionally the site of the Marquis of Cai’s ancestral temple and palace." Few villagers here bear the surname Wang, yet the place may well have taken its name from the royal mansion.

Many ancient wells, pottery drainage pipes and roof tile fragments have been found on the platform, proving that massive palace buildings once stood here, protected by moats all around. Local residents say small bronze artefacts and gold scraps are often washed out of the gully after heavy rain, hence its name the Gold-Scattering Ditch. A stone arch bridge spanning it is called the Gold-Scattering Bridge, where the royal treasury of Cai was said to be buried. "Visitors stroll along the brook; where do they hurry? Gold nuggets tumble in the rapid current," runs a local ballad describing people picking up gold after storms.

Shangcai occupied an exceptionally advantageous geographical position: it connected East Bugeng City and West Bugeng City to the west, Chen City to the east, Shaoling (east of present-day Yancheng, Henan) to the north, and the Huaihe River to the south. Surrounded by the winding Ruhe River and rolling hills, the city was easy to defend. As a transportation hub on the upper Huaihe River, Shangcai linked five major trade routes: west to Fangcheng, east to Shen and Xiang, south to Xi, northeast to Chen, and north to Zheng. By the late Spring and Autumn and early Warring States Periods, it had grown into a vital military stronghold outside Chu’s Fangcheng Great Wall.

Postal stations were established here before the Yuan Dynasty to facilitate nationwide transport. Chen Fu, a Yuan poet who once headed the Shangcai Academy, wrote the poem Postal Station of Shangcai County: Pheasants and hares grow fat beside Shangcai’s wall; Mulberries and jujubes weave a green barrier along the river. What joy it is to hunt with hounds out the East Gate; Why did the lord delay his homecoming so long?

The ancient South Gate still serves as a major north-south thoroughfare today. Fresh soil is piled beside the newly widened highway, flanked by two earthen ramparts — the remains of the ancient city wall, withered and bare in the cold winter. Near the gate, the rampart broadens noticeably, with a U-shaped sunken pit on its right: this is the barbican, a defensive outpost housing gate soldiers three thousand years ago.

Archaeological excavation found that the lower rammed earth contains pottery from the Yangshao, Longshan, Shang and Western Zhou cultures, while the upper strata hold relics of the Spring and Autumn and Warring States Periods. Based on these finds, archaeologists conclude that the city was first built in the Western Zhou Dynasty and repeatedly reinforced in later centuries.

More than 3,000 years ago, Shu Du founded the State of Cai, and Zhong of Cai restored it after its fall. Descendants adopted the state name as their surname, creating the Cai clan. All people surnamed Cai trace their ancestral root to Shangcai. In the Hundred Family Surnames compiled in the Song Dynasty, Cai ranked 155th. Modern surveys place it 44th nationwide and 8th among all surnames in Taiwan Province. All Cai descendants claim descent from the Ji royal house of Zhou. The Yuanhe Genealogy of Surnames of the Tang Dynasty records: "Shu Du, the fifth son of King Wen of Zhou, fathered Hu (Zhong of Cai). Enfeoffed in Cai, his descendants took the state as their surname after the state was conquered by Chu." As a branch of the royal Ji clan, the Cai family is also known as the Ji-Cai lineage.

A large earthen mound 1.5 kilometres west of Shangcai County seat is the 3,000-year-old tomb of Shu Du of Cai. Externally, the tomb mound is only larger than an ordinary rural grave. Three tall stone stelae stand before it, though they are of recent origin. An open altar area is reserved for clan worshippers. Surrounded by gullies and bare land without a single tree, the tomb looks bleak in northern winter. Fortunately, a memorial park is under construction, which will draw constant visitors in the future.

The founding marquis of Cai led a tragic life. After his failed uprising, he was confined on the outskirts of the state. Historical records note he "passed away in exile", a testament to his fiery temperament. Li Tianliang, former vice-chairman of the Shangcai Federation of Literary and Art Circles, holds a sympathetic view. In his 1997 Yu Opera Duke Shu of Cai, after the marquis is stripped of his fief and led into captivity, Zhou Gong Dan personally sees him off: "The long city stretches, ten li to the pavilion; Autumn wind blows amid mist and drizzle. Cups of thick homemade wine stand full; All sorrow remains unspoken between us." Li remarks that only Zhou Gong Dan and Shu Du truly knew the truth behind the political conflict.

The tomb of Zhong of Cai, Shu Du’s son, lies northeast of Caidu Town beside the Shangcai-Zhoukou highway. Similar in form yet smaller in scale, Zhong is remembered as a wise and sagacious ruler. He revived the family fortune at its lowest ebb and laid a solid foundation for the 600-year reign of the Cai royal house.

"Today the Cai clan is split into two branches," Li Tianliang explains. "Some honour Shu Du as the founding ancestor, while others regard Zhong of Cai as the true forefather of the surname." As long as they were father and son, the distinction matters little. Nine ancient tombs cluster near Shu Du’s burial mound, said to be the resting places of successive marquises of Cai. Overseas Cai clansmen are now planning to build a Marquis Mausoleum here.

The Ancient City Site of the State of Cai is a Major Historical and Cultural Site Protected at the National Level.