Overview
Key data
| Item | Detail |
|---|---|
| Excavated | Xiaotun, Yinxu, Anyang, Henan (found 1899; scientifically excavated from 1928) |
| Material | Turtle plastrons and ox scapulae |
| Period | Late Shang, from Wu Ding to Di Xin, over some 270 years |
| Day reckoning | The sexagenary cycle, sixty days to a round, already complete in the inscriptions |
| Month reckoning | Months numbered; an intercalary month written “thirteenth month” |
The calendrical content
The formula “On the guimao day divined: in the coming ten days there will be no calamity” is common, one divination per ten-day week. The week begins and ends on sexagenary days — direct evidence that Shang counted days in tens.
The months recorded are mostly twelve to a year, with a month added at the year’s end when needed and written as the “thirteenth month.” Attaching the intercalation to the year’s end was the rule in early practice.
Solar and lunar eclipse records
Among the inscriptions are a number of solar and lunar eclipses, among the oldest such records in the world.
They give modern astronomy fixed points for working back to the chronology of antiquity.
Value
The oracle bones push Chinese history with direct written records back to the late Shang. Several basic elements of calendrical order — sexagenary day-counting, the ten-day week, intercalation at the year’s end — are already formed in them.
The sexagenary day-count then ran unbroken for three thousand years; its source is here.
Compiled and arranged by Chujia Kuang.