Asian rice rotation systems

Timeline

1. 1451–1455Suzhou–Songjiang–Changzhou region · JiangnanDuring the Jingtai era, paddy management techniques in Jiangnan became more refined: the paired sowing system of early rice (indica) and late rice (japonica) stabilized in the core Suzhou-Songjiang-Changzhou rice region; local governments promoted repairs to polder waterworks, ensuring drainage in high-water periods and irrigation in low-water periods, raising per-mu yields over previous dynasties and laying the material foundation for tax collection in the Ming's Southern Zhili.
2. 1453–1458Lower Chao Phraya plain, around Ayutthaya · Siam (Thailand)Under King Borommatrailokkanat, the Kingdom of Ayutthaya carried out administrative reforms, and its rice production and tribute system became more standardized; floating-field rice cultivation on the Chao Phraya floodplain used seasonal floods for natural fertilization, giving stable yields and making Ayutthaya one of mainland Southeast Asia's most important rice-export sources, attracting resident Chinese merchant traders.
3. 1456–1460Red River delta · VietnamVietnam's early Lê dynasty implemented land reforms and military agricultural colonies under Nhân Tông and Thánh Tông; the Red River delta was systematically integrated into a state-controlled rice economy. Repairs to dikes and canals expanded double-cropping, stabilizing grain supply in the northern plain and supporting military expansion southward against Champa through tax revenue.