As commented elsewhere, visiting important historic ruins - like Angkor - without understanding the sights would probably spoil the event. Ayutthaya is not different; moreover, comprehending its history is key to understanding modern Thailand. The kingdom of Ayutthaya was the second Thai kingdom, following the one in Sukhothai and preceding the one in Thonburi/Bangkok; it existed from 1351 to 1767AC.
In an attempt to escape the threat of an epidemic, King Ramathibodi I founded Ayutthaya as the capital of his kingdom in 1351; the city was named after the Hindu holy city Ayodhya in northern India, the birth place of the Hindu god Rama, the Ramayana Hindu epic hero.
In 1360, Ramathibodi declared Theravada Buddhism the official religion of Ayutthaya and brought members of a sangha, a Buddhist monastic community from Sri Lanka to establish the kingdom's religious order. He also compiled a legal code based on the Indian Dharmashastra and Thai custom; supplemented by royal decrees, this legal code remained in use until the late nineteenth century.
Ramathibodi seized Angkor in the last year of his reign, during the first of several successful Thai assaults on the Khmer capital. The Khmer often submitted to Ayutthaya's suzerainty, but the Thai efforts to maintain control over Angkor were futile since Thai troops were frequently diverted to suppress rebellious Sukhothai or to fight the Lanna Kingdom (Chiang Mai), where Ayutthaya's expansion was resisted.
In 1376AC Sukhothai was finally annexed to his kingdom. Over the next four centuries the kingdom expanded to become Siam, whose borders were roughly those of modern Thailand, except for the northern Lanna Kingdom. Eventually Ayutthaya prevailed, and the year after Ramathibodi died, his kingdom was recognized by the Ming Chinese emperor as Sukhothai's rightful successor.
The kingdom was not a single, unified state but rather a group of self-governing principalities and tributary provinces ruled by the king of Ayutthaya under the mandala system (see that entry in this journal). The principalities were ruled by members of the royal family of Ayutthaya who had their own armies and warred among themselves, and the autonomous southern Malay states.
Soon, Ayutthaya's kings began expanding the kingdom systematically. In 1431AC, Angkor, the Khmer capital, was destroyed by Ayutthaya. Abandoning it, the Khmer relocated their capital in Phnom Penh, a site which was easier to defend.
During much of that century, Ayutthaya's energies were focused on the Malay Peninsula, where the port of Malacca claimed sovereignty. Ayutthaya's failed due to the Chinese military support of the Sultanate. The Chinese Admiral Zheng had one of his bases there, so the Chinese could not afford to loose such a strategic position to the Thais. Under this protection, Malacca flourished into one of Ayutthaya's great rivals, until its conquest in 1511 by the Portuguese. An important detail in this saga, was that Malacca and other Malay states had become Muslim; the new religion became a unifying symbol against the Thais.
After conquering Malacca, the Portuguese sent in the same year a diplomatic mission to Ayutthaya. Five years after that, Ayutthaya and Portugal signed a treaty granting the Portuguese permission to trade in the kingdom. In 1592, another treaty gave the Dutch privileges in the rice trade.
Burma raised during the sixteenth century; it conquered the Lanna Kingdom and Laos, and was eyeing Ayutthaya.
In 1569 Burmese forces, joined by Thai rebels of the Thai royal family, captured Ayutthaya and deported the royal family to Burma. Dhammaraja, a Thai governor who had aided the Burmese, was installed as vassal king at Ayutthaya. Thai independence was restored by his son, King Naresuan (1590- 1605), who turned on the Burmese and expelled them from the country in 1600.
This new dynasty welcomed foreigners; important commercial ties were forged with Japan. Dutch and English companies were allowed to build factories, and Thai diplomatic missions were sent to Paris and The Hague. The Thai court skillfully played off the Dutch against the English and the French, avoiding the excessive influence of a single power and probably ensuring its future survival of the colonial period relatively unharmed.
In 1664, the Dutch used force to get a treaty granting them extraterritorial rights as well as freer access to trade. Following his Greek foreign minister advise, Constantine Phaulkon, King Narai requested French help; those built fortifications for the Thai and a new palace at Lopburi. In parallel, French missionaries engaged in education, brought the first printing press into the country and began a comprehensive health project. Louis XIV's personal interest was driven by reports from missionaries suggesting that Narai might convert to Christianity.
The French presence caused suspicion among the Thai nobles and Buddhist clergy. When King Narai was dying, general Phetracha killed both the Christian heir and Phaulkon, along with the missionaries. The arrival of English warships caused a massacre of more Europeans. General Phetracha seized the throne, expelled the foreigners, and began a period of a century and a half during which the Thais isolated themselves from the West.
After this violent episode, Ayutthaya entered its golden age, a relatively peaceful period in the second quarter of the eighteenth century when art, literature, and learning flourished. The Ayutthaya fought with the Vietnamese Nguyen Lords over the control of Cambodia from1715 onward, and on the west the new Alaungpaya Burmese dynasty had temporarily conquered the Shan, but overall big struggles seemed as part of the past.
By the mid eighteen century, Ayutthaya's territory included the Shan, Lanna, parts of Yunnan and Shan Sri in China, Lan Xiang in northern Laos, Cambodia, South Vietnam and some of Malaya.
In 1765, the Thai territory was invaded by two Burmese armies that converged on Ayutthaya, meeting no resistance except for that of the village of Bang Rajan. After a lengthy siege, Ayutthaya was burned in 1767. Ayutthaya's art treasures, temples, palaces and libraries were almost completely destroyed.
The Thais were saved from Burmese control by a Chinese invasion of Burma. Shortly after, the Thai general Phraya Taksin managed to reunify the country, became king and moved his capital southwards to Thonburi, across the Chao Phraya River from modern Bangkok.