The Forty Years' War (Burmese: အနှစ်လေးဆယ်စစ်; 1385 – 1424; also Ava-Pegu War or the Mon-Burmese War) was a military conflict fought between the Burmese-speaking Kingdom of Ava and the Mon-speaking Kingdom of Hanthawaddy Pegu. The war was fought during two separate periods: 1385 to 1391 and 1404 to 1424, interrupted by two truces of 1391–1404 and 1406–1407. It was fought primarily in today's Lower Burma and also in Upper Burma, Shan State and Rakhine State. It ended in a stalemate, preserving the independence of Hanthawaddy, and effectively ending Ava's efforts to rebuild the erstwhile Pagan Empire.