Extended Data Fig. 2: Gordion tree-rings series and crossdating grid.
From: Severe multi-year drought coincident with Hittite collapse around 1198–1196 bc
a, Raw (non-standardized) measured tree-ring series for the Gordion samples (all same scaling on Y axis) indicating the overall growth trends in each case. b, Crossdating grid for the Gordion tree-ring samples listing the Baillie-Pilcher t-scores (upper value) and length of overlap in rings/years (lower value) for each sample series versus the others from COFECHA74. Potentially satisfactory values where there is strong overlap (e.g. > 50-100 years) are tBP ≥3.5 (unsatisfactory values are indicated by grey shading)—although in reality higher tBP-values are necessary for a secure match (see Methods). Higher values and especially tBP-scores >5-6 usually indicate a good crossdate. Here all samples exhibit at least several strong to very strong crossdates against a number of other samples in the chronology with long overlaps, demonstrating an overall robust chronology.
