Hunch Not checked yet 1555 BC

The early books remember failed harvests, mixed cold and heat and a five-year drought at the Xia's end; the ice cores show four eruptions in 1561-1550 BC, about when Erlitou ended

Opened 26 October 2026. What survives the checks: texts written long before any ice-core science (Mozi, Guoyu, Lushi Chunqiu) agree that the change of dynasty came with crop failure, cold and heat out of season, the Yi and Luo running dry and a multi-year drought. Big northern eruptions weaken the East Asian summer monsoon, which brings drought to the Yellow River plain. The decade 1561-1550 BC holds four eruptions (about 55 Tg S together), and the end of Erlitou (about 1530-1500 BC) is close but blurred by the radiocarbon plateau. Base rate: the window 1680-1500 BC has 11 eruptions of 5 Tg S or more, so any 30-year span has about two; the cluster is notable. Ring test (a-xia-rings, same day): far to the west, juniper rings show 1561-1546 BC in the driest tenth of 1800-1300 BC with sharp dry years in 1558 and 1548 BC, and a hint of narrow rings two years after eruptions (about 0.2 once the lags tried are counted). Weak support, from the wrong place. Still needed: a calendar-dated record from the Yellow River plain, or tighter dates for the end of Erlitou. Pang's team made the same broad pairing in 1989 with the old ice-core dates.

Tests we ran on this

No sign 0.1 Was 1561-1546 BC unusually dry in the Qilian juniper rings? Somewhat: 50th driest of 486 sixteen-year windows. (decided before looking, 2026-10-26) · scoreboard
Passed 0.03 Are the rings narrow two years after each of the 11 eruptions? Yes at 2 years, but 7 lags were tried, so about 0.2 really. (chosen after looking, 2026-10-26) · scoreboard

How it connects

This hunch is about Why did the Xia dynasty fall (about 1600 to 1530 BC), and do the omens told of its end remember a real eruption?

This hunch we read it in JPL news release, 1 Dec 1989: Pang, Srivastava, Keston and Chou date Thera to the late 17th century BC from Chinese records of King Jie (dim sun, three suns, frost in the 6th month, seven-year drought), matched to the Greenland ice cores and tree rings of the time (AGU Fall Meeting 1989) same broad pairing, older ice dates

This hunch is supported by Ice cores: 1561-1550 BC was the busiest volcanic stretch of 1680-1500 BC (four eruptions in 12 years), and 1561 BC is the 2022 best guess for Thera four eruptions 1561-1550 BC

This hunch is supported by Juniper rings (Qilian Mountains, 1,400 km west of Erlitou): 1561-1546 BC was somewhat dry, with sharp dry years in 1558 and 1548 BC, from only 12 cores weak: drier decade, dry 1558 and 1548 BC

This hunch is supported by Erlitou's last phase is dated about 1565-1530 BC, around the 1561-1550 BC eruptions; but the other proposed Xia-Shang boundary (about 1635-1610 BC) sits near the 1628 and 1611 BC eruptions too fits, but so would almost any date

This hunch is supported by Mozi (about 400 BC): under King Jie 'sun and moon were out of time, cold and heat came mixed, the five grains scorched and died' old memory of crop failure and drought

This hunch came from this step Started the end of the Xia: the Bamboo Annals' 'three suns' lands on the 1561 BC eruption, but only by chance

This hunch has this hunch or step Looked for dry years in 1561-1550 BC in the raw juniper rings of the Qilian Mountains