According to histories, Predynastic Zhou rose as a western vassal of the Shang, acting as its ally until their influence surpassed that of the dynasty.
After the fall of Shang, the Ji clan established the Zhou dynasty and started their own narrative about previous generations.
Predynastic Zhou, having existed about three centuries earlier, proves to be difficult when historians try to find its beginning and end year.
Zhou official texts record various astronomical events, whose time can be calculated by scientific laws; that gives an advantage in deciding the exact period.
The Xia-Shang-Zhou Chronology Project, an ambitious collaboration of Chinese historians commissioned by the People's Republic of China in 2000, produced a draft report that identifies Gugong Danfu's first year of rule as 1158 BC, around the reign of Shang king Geng Ding.
Ji Fa's ascension to power is of historical interest, since his life revolved around heavenly signs that have been proved to be true.
However, the American sinologist David Nivison studied the information given by the Bamboo Annals, and suggested the Shang dynasty's beginning year to be 1558 BC.
His court carved a large portion of the total inscriptions mentioning Zhou; however, they only provide the king's perspective towards the country.
[3] Wu Ding referred to the Ji clan and its subordinates as "Zhou Fang" (周方), a common naming traditions that the Shang used to address neighboring polities.
According to Sima Qian, Predynastic Zhou was established by Gugong Danfu when he relocated his clan from their home of Bin to a new settlement near the Mount of Qi called Zhouyuan (周原) along the Wei River.
[5] His two elder sons Taibo and Zhongyong were said to have abandoned the territory and fled south to establish Wu on the lower Yangtze.
His youngest son Jili then inherited Zhou and expanded it with numerous campaigns against the Rong "barbarians" around Shang.
To ensure Zhou's power before countering Di Xin's army, Ji Chang launched numerous expansion campaigns.
His target included the Shang dynasty's long-term hostile polities that had already been weakened by Wu Ding almost 200 years earlier.
Almost all regional lords that had been subdued by Ji Chang allied with Fa, finally crushed the Shang armed forces.
[6] Complying with Predynastic Zhou's patrilineal succession traditions, the one chosen by Heaven had to be the eldest male child of the current ruler.
[7] According to Zhou's narrative, the final Shang king Di Xin was a decadent, and therefore no longer authorized to receive the Mandate of Heaven.
In May, the densest clustering in five hundred years' time of the five planets visible to the naked eye could be seen in the constellation of Cancer, followed a few seasons later by an apparition of Comet Halley.
Early records, such as the inscription on the Da Yu ding, describe Heaven's Mandate in terms of an actual astronomic event: "the great command in the sky" (天有大令).
The subsequent generations of the Zhou dynasty developed the concept into a system that would dictate the Chinese monarchy for approximately 3000 years.