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Accumulated Δ13C mean record from 1.037 barley grains from 33 archaeological sites (black line). Red line, reference line for drought stress at 16‰ and below; blue line, reference line for favorable conditions at 17‰ and above; red bars, global climatic fluctuations at roughly 5200 B.P. (➀), 4200 B.P. (➁), and 3200 B.P. (➂).
