The Burmese–Siamese War (1547–1549), also known as the Shwehti war was the first war fought between the Toungoo dynasty of Burma and the Ayutthaya Kingdom of Siam, and the first of the Burmese–Siamese wars that would continue until the middle of the 19th century. The war is notable for the introduction of early modern warfare to the region. It is also notable in Thai history for the death in battle of Siamese Queen Suriyothai on her war elephant; the conflict is often referred to in Thailand as the War that Led to the Loss of Queen Suriyothai (สงครามคราวเสียสมเด็จพระสุริโยไท).

The Toungoo dynasty, and also known as the Restored Toungoo dynasty, was the ruling dynasty of Burma (Myanmar) from the mid-16th century to 1752. Its early kings Tabinshwehti and Bayinnaung succeeded in reunifying the territories of the Pagan Kingdom for the first time since 1287 and in incorporating the Shan States for the first time, in addition to including Manipur, Chinese Shan States, Siam and Lan Xang. At its peak, the Toungoo Empire was the largest and strongest empire in Southeast Asia. However, it collapsed in the 18 years following Bayinnaung's death in 1581.