Late Tang hydroclimate swings strained northern China
Cooler, drier, and flood-prone conditions after 800 CE made Yellow River crop and supply networks increasingly fragile.
Source
Hydroclimatic instability accelerated the socio-political decline of the Tang Dynasty in northern China
What they did
The authors combined a tree-ring Yellow River runoff reconstruction (800–907 CE) with a drought–flood vulnerability model, crop-suitability maps, and 53 least-cost food-supply networks across the Yellow River Loop.
What they found
After 800 CE the region shifted cooler and drier, with harvests often poor between 800 and about 840 CE, floods recorded more than 1500 times over the last millennium (up to three per year), a humid high-runoff pulse around 880–900 CE, then a sharp runoff and precipitation drop after 900 CE. Late Tang military sites sat near the 400 mm/year isohyet in drought- and flood-prone ground, while wheat and rice replaced more drought-tolerant millet.
The limits
What it doesn't show
Network models cannot prove climate caused the 907 CE collapse; rebellion and war still matter. CHELSA climate fields are modern analogues, and documentary floods and harvest grades have uneven coverage.
Key terms
- East Asian Summer Monsoon (EASM)
- The seasonal moisture influx that supplies just over half of annual rain in the southeastern Yellow River basin between June and August.
- Yellow River Loop (YRL)
- The northern bend of the Yellow River, a farming–pastoral frontier sensitive to the 400 mm/year rainfall line.
- Climatic water balance (CWB)
- Precipitation minus potential evapotranspiration; strongly negative CWB marks drought-vulnerable crop zones.
Flashcards
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The 400 mm/year isohyet in this paper marks:
Common questions
What climate archive constrained river flow?
An annually resolved Yellow River streamflow reconstruction from tree rings, subset to 800–907/908 CE and compared with pre-1960 natural-flow conditions.
Why did wheat make the system more fragile?
Late Tang agriculture shifted from drought-tolerant millet toward wheat and rice, which fail more readily in cool, dry years.
Where were new garrisons placed?
Near the 400 mm/year isohyet on the northern frontier, in zones of high drought and flood risk.
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