干旱区生态环境知识资源中心

The analysis of 718 Holocene dates from lake deposits (present-day Sahara) and palaeosols (arid zones in China), testifies to in-phase climatic variations in both regions: two optimal periods during the Early Holocene and around 5 ka, two more arid episodes, at 6.7 to 5.5 ka and at 4 to 3.6 ka. The latter was very severe; it culminated at 3.8 ka and ruined ancient civilizations and socio-economic systems. These results fit marine records in the Arabian Sea and the China Sea. The Holocene optimum did not therefore occur at c. 6 ka in the areas considered.