After a bloody period of dynastic struggle, Ayutthaya entered into what has been called the Siamese "golden age", a relatively peaceful episode in the second quarter of the 18th century when art, literature, and learning flourished. There were seldom foreign wars, apart from conflict with the Nguyễn Lords for control of Cambodia starting around 1715. The last fifty years of the kingdom witnessed bloody succession crises, where there were purges of court officials and able generals for many consecutive reigns. In 1765, a combined 40,000-strong force of Burmese armies invaded it from the north and west. The Burmese under the new Alaungpaya dynasty quickly rose to become a new local power by 1759. After a 14-month siege, the capital city's walls fell and the city was burned in April 1767.