King Narai the Great was the son of King Prasatthong. He was a great warrior with sufficient armed forces to protect the Kingdom. In 1662, King Narai sent troops to attack Burma and Chiang Mai. His numerous conquests and victories glorified Siamese military might throughout Asia. At this time, it was said among foreigners in Ayutthaya that of all the Asian natives, the Kingdom of Siam was the most powerful with an incomparably magnificent Court.  

Above all of his well-known characteristics, King Narai was the most outward-looking and cosmopolitan ruler during the reign of Ayutthaya. Like all Siamese kings, King Narai was the upholder of all faiths in the Kingdom. Bishop Pierre Lambert de la Motte said that, except for Siam, there was nowhere in the world where various natives could live together in liberty of conscience.

As for foreign relations, King Narai became the most renowned Thai monarch since he adopted a friendly policy towards foreigners, especially the Europeans. Ayutthaya was a metropolis where peoples from many lands congregated, including the Dutch, the British, the French, the Portugese and the Arab. The French, who first arrived in 1662, sent missionaries and merchants to the capital. During the 1680's, splendid embassies were exchanged between King Narai and King Louis XIV. Later on, the conflict broke out when the French tried to convert King Narai to Christianity and also attempted to gain a foothold in the Thai kingdom by sending troops to garrison Bangkok and Mergui in 1687. However, an anti-French official seized power in 1688, drove out the French garrisons, and executed King Narai's Greek favorite Constantine Faulcon, who had been championing the French cause. After 1688, Ayutthaya had less contact with western nations.

The Thai Kingdom under the reign of King Narai was abundant in agricultural produce. Siam did a lot of trade with merchants from different parts of the world. During his prosperous reign, Siam was always crowded with hundreds of vessels of all sizes from both Asia and Europe.

K ing Narai himself was a poet, and Thai literature was revived during his reign. Under his patronage, his Court became the center where poets congregated to compose verses and poems. King Narai certainly made his poetic mark in the history of Thai literature and enjoyed the literary works, which were admirably produced by such outstanding poets as Pra Maharajkru, Pra Horatibodi, and Sriprachya. At the command of King Narai, Pra Horatibodi wrote a book for the study of Thai language entitled Chindamani, in order to counter balance the French cultural influence. The King worried about Thai children who attended the catholic schools in increasing numbers, as they might adopt the European culture and be converted. Summing up the elements, the grammar, the prosody, the versification of Thai language as well as official forms of correspondence, the Chindamani became a popular textbook in due time and continued to be in use until the commencement of King Chulalongkorn's reign (1868-1910). It is generally accepted as the first textbook of Thai language.