An Alternative Model Linking the Thera Eruption with Chinese Chronology

(Modified 7 May 2025) The last post discussed the evidence that seemingly links the eruption of Thera with events during the transition from the Chinese Xià Dynasty (夏朝 Xiàcháo) to the Shāng (商朝 Shāngcháo).

The Bamboo Annals describe two types of events associated with this transition period that might be related to the eruption. It states that in the 29^th year of the last Xià Dynasty king, Xià Jié, “three suns appeared together,” describing a sun dog. It also detailed that a drought began in the 19^th year of Chéng Tāng (成湯) and lasted into his 24^th year. Those years were his second through seventh years as the first emperor of the Shāng Dynasty. However, admittedly, neither sun dogs nor droughts are necessarily the consequences of volcanic eruptions. (I witnessed sun dogs twice during recent winters.)

Still, as noted in David Pankenier’s article about the effects of the Thera eruption in China (pp. 771-3), later writers such as Mozi 墨子 connected severe climate effects with the Xià-Shāng transition period. Did the sun dog, drought, and other climatic events recalled by later writers result from the Thera eruption? If that event did occur during this transition period, Shan Ling’s chronological model, discussed previously, must be correct or at least approximately so. This post presents an alternate model that is likely precisely accurate.

The Bamboo Annals briefly mention an astronomical event in the 10^th year of Xià Jié: 五星錯行 wǔxīng cuò xíng, which could mean “The five [visible] planets chaotically moved.” Centuries later, some commentators incorrectly understood this was another instance of the five planets aligning as it had done in May 1059 BCE. They believed this event was another Mandate of Heaven (天命 Tiānmìng), which indicated a virtuous leader should overthrow the corrupted Xià Dynasty. Based on the 516.33-year cycle of the triple conjunction of Saturn, Jupiter, and Mars, they calculated that 五星錯行 had occurred in 1576 BCE, and they incorrectly concluded that it was Xià Jié’s 10^th year. This understanding led to the erroneous conclusion that the Shāng Dynasty had lasted approximately five centuries. (Cf. Pankenier, 1981, pp. 17-21.)

Author Shan Ling 凌山 noted that a source (Yù Zǐ 鬻子) contemporary with the final emperor of the Shāng Dynasty, Dì Xīn (帝辛), wrote that this monarch’s tenure began 576 years after Chéng Tāng’s. The Xia-Shang-Zhou Chronology Project assigned Dì Xīn’s first year of rule to 1075 BCE. Counting back 576 years places Chéng Tāng’s defeat of Xià Jié during his 31^st and final year in 1651 BCE. With the assumption that Chéng Tāng’s first year as the new emperor (his 18^th year as a regional king) was the following year (1650), four additional pieces of the puzzle fall into place with this first piece:

Second: As mentioned in the previous post, Shan Ling 凌山 cited Liú Xīn 劉歆, who stated the duration of the Shāng Dynasty was 629 years. Thus, he wrote that this dynasty lasted from 1675 to 1046 BCE. In a private communication, Shan Ling kindly provided the source of the triple combination (甲子朔旦冬至) of a winter solstice, astronomical dark moon, and first day (甲子) of the Gānzhī (干支 sexagenary) cycle, which was Volume 21 of The Book of Han. The first-century-CE author, Bān Gù 班固, commented on some chronological viewpoints of other scholars and offered a corrected understanding. He wrote that this 629-year period ended in the fifth year [1038 BCE] of Zhōugōng (周公, the “Duke of Zhou”), which was several years after the Shāng Dynasty’s end in 1046 BCE. With this premise, that dynasty began in 1667 BCE, 16 years before Chéng Tāng’s 17^th year and his defeat of Xià Jié in 1651.

Third: The severe drought during Chéng Tāng’s 19^th through 24^th years occurred in 1649-44 BCE, immediately after the Thera eruption in 1650.

Fourth: Two out of three aspects of Shan Ling’s triple combination (甲子朔旦冬至) did occur near the end of his 12th year as emperor. In January 1638, the winter solstice was at 23:25 on 3 January, and the astronomical dark moon occurred at 03:50 on 4 January, just a few hours later. Nevertheless, neither date was the first day of the Gānzhī cycle, 甲子. Bān Gù’s sexagenary cycle dates were unreliable. A comparison of his other Shāng Dynasty Gānzhī cycle dates with dated Oracle Bone inscriptions of astronomical events proves they do not harmonize.

Fifth: With Xià Jié’s 31^st year in 1651 BCE, his 10^th year was in 1672. Professor Pankenier translated 五星錯行 as “crisscrossing planets” because “crisscross” is another meaning of 錯 cuò. In this context, cuò could connote planetary invisibility when the planets are too near the Sun to be visible and cross between their heliacal setting in the west and heliacal rising in the east. Moreover, Pankenier linked this event with “Great Fire,” the star Antares in the Scorpius constellation. (1981, pp. 18-19, 21)

The illustration above shows this occurred in 1672 BCE when the Sun’s position was next to Antares. Mercury was transiting the Sun, and Venus was crossing in the opposite direction on the far side of its orbit; thus, the two planets literally crisscrossed. Moreover, Saturn had recently crossed from evening visibility to morning, and Mars and Jupiter were in the process of doing so. Four of the five planets were invisible in the night sky.

This discussion reveals that two distanzangabens, one contemporaneous, precisely fit the premise that the Thera eruption occurred in the Xià-Shāng dynastic transition period, and two sets of astronomical details provide additional supporting evidence of this model’s accuracy. Since five puzzle pieces fit together harmoniously, we can conclude with almost 100% certainty that Chéng Tāng’s first year as a duke was 1667 BCE, and his first year as emperor was 1650 BCE.