The Burmese-Siamese War of 1584–1593, also know as the Nandric War, was a series of conflicts between the Toungoo Dynasty of Burma and the Ayutthaya Kingdom of Siam. The war began when Naresuan, the King of Ayutthaya, declared independence from Burmese suzerainty, renouncing his vassal status. This action led to several Burmese invasions aimed at subduing Ayutthaya. The most notable invasion was led by the Burmese Crown Prince Mingyi Swa in 1593, which resulted in the famous elephant duel between Mingyi Swa and Naresuan, where Naresuan killed the Burmese prince.

Following the death of Mingyi Swa, Burma had to withdraw its forces, leading to a shift in power dynamics in the region. This event greatly boosted the morale of the Siamese troops and helped solidify Naresuan's status as a hero in Thai history. Ayutthaya took advantage of the situation to launch counter-attacks, capturing several cities and regaining territory that had previously been lost to the Burmese. These military gains weakened Burmese influence in the region and strengthened Ayutthaya’s position.

The Burmese-Siamese War significantly altered the balance of power in Southeast Asia. While it ended inconclusively, the conflict weakened Burmese influence and power while bolstering Ayutthaya's independence and regional standing. The war is particularly famous for the elephant duel, which is a seminal event in Thai history, often cited as a symbol of national heroism and resistance against foreign invasion. It set the stage for ongoing conflicts and fluctuating relations between the two kingdoms, which continued for centuries.