Chengtoushan is a Neolithic settlement northwest of Dongting Lake in Hunan China. Site contains world's earliest rice paddies dating 4500-3000 BC. Settlement spanned Daxi, Qujialing, and Shijiahe cultures. Abandoned mid-Shijiahe period. Round settlement surrounded by moat and rammed earth wall built in Daxi culture. Wall and moat constructed around 4000 BC and lasted two millennia. Human sacrifices found under wall foundation. Gravel road, river bridge, and river-control gate discovered. Oldest known walled site in China. Earliest fired bricks date to 4400 BC made from red clay loess. Bricks fired above 600°C on all sides used for house flooring. By 3300 BC Qujialing period bricks paved roads and formed building foundations. Site located 12 km northwest of Li County seat.