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Rice agriculture is the foundation of Asian civilizations south of the Yangtze River. Although rice history is well documented for its lower Yangtze homeland area, the early southward expansion of paddy rice farming is poorly known. Our study investigates this process using a compilation of paleoenvironmental proxies from coastal sediment cores from southeast China to Thailand and Island Southeast Asia. We propose that a shortage of land suitable for paddy fields, caused by marine transgression, constrained rice agriculture during the mid-Holocene. Rapid expansion of coastal plains, particularly in deltaic basins, over the past three millennia has coincided with increases in land suitable for rice cultivation. Our study also helps explain the past population movements of rice farmers. [ABSTRACT FROM AUTHOR]

Neolithic agricultural development and environmental effects in the Longdong area were reconstructed using a synthetic approach, investigating pollen, charcoal, and seed remains for two cultural layer sections and five flotation sites. Results show that Neolithic agriculture in the Longdong area had a simple organization and was dominated by the production of common millet, especially in the early and middle Yangshao age. After the late Yangshao age, Neolithic agriculture developed into a more complex structure, dominated by both common and foxtail millet and the cultivation of rice and soybeans. The production of foxtail millet gradually increased through the Neolithic period, reaching its highest point during the Qijia culture. Soybeans were first cultivated during the late Yangshao culture, approximately 5000 cal a BP. Rice production began no later than 4800 cal a BP, and continued to exist in the Qijia culture, approximately 4000 cal a BP. Agricultural production in Neolithic Longdong, specifically in the "Yuan" area of the loess plateau, developed as a shrub and grass dominated landscape. Vegetation in the river valleys was partly covered with Picea, Tusga, and Quercus coniferous and broadleaf mixed forests. Agricultural activity during the Neolithic period caused an increase in farmland on the loess tableland and a decrease in the abundance of shrub and grassland in the Longdong area. When farmlands were abandoned, vegetation recovered with Hippophae-, Rosaceae-, Ephedra-, and Leguminosae-dominated shrublands and Artemisia-dominated grasslands. [ABSTRACT FROM AUTHOR]