Nilometer to Geniza

Claim (verbatim)

Nilometer to Geniza. This joins two of the medieval world's best data series: the Nilometer readings of the Nile's annual flood, kept for centuries at Cairo, and the grain prices preserved in the Cairo Geniza's merchant letters. Egypt's harvest was the flood: a low Nile meant fields unwatered and grain scarce, but only after the agricultural cycle ran its course — sowing, growth, harvest, and marketing take the better part of a year. The conjecture therefore predicts that Cairo grain prices follow Nilometer minima with a fixed lag of about nine months, and that the response is asymmetric: droughts move prices more than good floods do, because hoarding and panic amplify scarcity while abundance merely eases into storage. Joining the two series should reveal a lagged, kinked relation — a medieval macroeconomic transmission mechanism measurable at nearly annual resolution.

Prediction clause (verbatim)

For the joined series of Nilometer flood minima and Geniza-attested Cairo grain prices, align each year's flood reading with prices roughly nine months later and fit the price response to flood deviations, allowing separate coefficients for below-normal and above-normal floods. Primary clause: the lagged relation must peak in the 6-to-12-month window with low floods significantly predicting higher prices, and the drought coefficient must exceed the good-flood coefficient in magnitude by at least a factor of 1.5; a symmetric price response, or no significant relation at the predicted lag, falsifies the claim. The verdict follows the primary clause.

Kill-dataset (verbatim)

joined series.

Novelty / leakage triage

already answered in the literature

The Nilometer-to-grain-price join is established: medieval Egyptian flood-failure/famine/price linkage is documented in the extreme-floods-and-famines literature (AD 930-1500) and in pre-modern price studies; nilometer readings were used administratively to forecast harvests and set taxation. The 9-month fixed lag and asymmetric response are sharper than anything located, but the connection is published. Chosen partly as a calibration suspect and confirmed leaked.

• 'Extreme Nile Floods and Famines in Medieval Egypt (AD 930-1500) and Their Climatic Implications' — Flood-famine-price linkage, medieval Egypt
• 'Reconstructing the Nile: climate, agriculture, and socio-economic change in Roman Egypt' — Flood-economy coupling

Its literature citations feed the frontier as source leads (2 leads below the evidence/publication boundary, not yet reviewed).

Predictions

No prediction registered yet.