Thonburi and Bangkok period

After more than 400 years of power, in 1767, the Kingdom of Ayutthaya was brought down by invading Burmese armies, its capital burned, and the territory split. General Taksin managed to reunite the Thai kingdom from his new capital Thonburi and declared himself king in 1769. However, Taksin allegedly became mad, and he was deposed, taken prisoner, and executed in 1782. General Chakri succeeded him in 1782 as Rama I, the first king of the Chakri dynasty. In the same year, he founded the new capital city Bangkok, across the Chao Phraya River from Thonburi, Taksin's capital. In the 1790s Burma was defeated and
driven out of Siam, as it was then called. Lanna also became free of Burmese occupation, but the king of a new dynasty who was installed in the 1790s was effectively a tributary ruler of the Chakri monarch.
The heirs of Rama I became increasingly concerned with the threat of European colonialism after British victories in neighboring Burma in 1826. The first Thai recognition of Western power in the region was the Treaty of Amity and Commerce with the United Kingdom in 1826. In 1833, the United States began diplomatic exchanges with Siam, as Thailand was called until 1939, and again between 1945 and 1949. However, it was during the later reigns of King Mongkut (1804–1868), and his son King Chulalongkorn (1853–1910), that Thailand established firm rapprochement with Western powers. It is a widely held view in Thailand that the diplomatic skills of these monarchs, combined with the modernizing reforms of the Thai Government, made Siam the only country in Southeast Asia to avoid European.
colonization. This is reflected in the country's modern name, Prathet Thai or Thailand, used since 1939 (although the name was reverted to Siam during 1945–49), in which prathet means "nation".
The Anglo-Siamese Treaty of 1909 defined the modern border between Siam and British Malaya by securing Thai authority over the provinces of Pattani, Yala, Narathiwat, and Satun, which were previously part of the semi‐independent Malay sultanates of Pattani and Kedah. A series of treaties with France fixed the country's current eastern border with Laos and Cambodia.

Ayutthaya Period

For 417 years the kingdom of Ayutthaya was the dominant power in the fertile Menam or Chao Phraya Basin. Its capital was Ayutthaya, an island city situated at the confluence of three rivers, the Chao Phraya, the Pasak, and the Lopburi, which grew into one of Asia's most renowned metropolises, inviting comparison with great European cities such as Paris. The city must indeed have looked majestic, filled as it was with hundreds of monasteries and crisscrossed with several canals and waterways which served as road

Ayutthaya, the capital of the Thai Kingdom was founded by U-Thong King in 1350. Ayutthaya as an island is formed by the gathering of three rivers, the Chao Phraya, the Pasak, and the Lopburi, and is surrounded by rice terraces. It is easy to see why the Ayutthaya area was settled before this date since the site offered a variety of geographical and economic advantages.  Not only is Ayutthaya at the confluence of three rivers, plus some canals, but its proximity to the sea also gave its inhabitants an irresistible stimulus to engage in maritime trade. The rice fields in the immediate environs flooded each year during the rainy season, rendering the city virtually impregnable for several months annually. These fields, of course, had an even more vital function, that of feeding a relatively large population in the Ayutthaya region. Rice grown in these plants yielded a surplus large enough to be exported regularly to various countries in Asia.
The Thai kings of Ayutthaya became powerful in the 14th and 15th centuries, taking over U-Thong, Lopburi, and Ayutthaya. Ayutthaya's first king, Ramathibodi I, was both a warrior and a lawmaker. Some old laws codified in 1805 by the first Bangkok king date from this much earlier reign. King Ramathibodi I and his immediate successors expanded Ayutthaya's territory, especially northward towards Sukhothai and eastward towards the Khmer capital of Angkor. By the 15th century, Ayutthaya had established a firm hegemony over most of the northern and central Thai states, though attempts to conquer Lanna failed. Ayutthaya also captured Angkor on at least one occasion but was unable to hold on to it for long. The Ayutthaya kingdom thus changed, during the 15th century, from being a small state primus inter pares among similar states in central Thailand into an increasingly centralized kingdom wielding tight control over a core area of territory, as well as having looser authority over a string of tributary states.
King U-Thong and his immediate successors expanded Ayutthaya's territory, especially northward towards Sukhothai and eastward towards the Khmer capital of Angkor. The greater size of Ayutthaya's territory, as compared with that of Sukhothai, meant that the method of government could not remain the same as during the days of King Ramkhamhaeng. The paternalistic and benevolent Buddhist kingship of Sukhothai would not have worked in Ayutthaya. The king of the latter, therefore, created a complex administrative system allied to a hierarchical social system. This administrative system dating from the reign of King Trailok, or Borommatrailokanat(1448-1488), was to evolve into the modern Thai bureaucracy. The Ayutthaya bureaucracy contained a hierarchy of ranked and titled officials, all of whom had varying amounts of "honor marks" (Sakina).
Thai society during the Ayutthaya period also became strictly hierarchical. There were, roughly, three classes of people, with the king at the very apex of the structure. At the bottom of the social scale, and the most numerous, were the commoners (freemen or phrase) and the slaves. Above the commoners were the officials or "nobles" (shunning), while at the top of the scale were the princes (chao). The one classless sector of Thai society was the Buddhist monkhood, or sangha, into which all classes of Thai men could be ordained. The monkhood was the institution that could weld together all the different social classes, the Buddhist monasteries being the center of all Thai communities both urban and agricultural.
The Ayutthaya kings were not only Buddhist kings who ruled according to the dhamma (dharma), but they were also devaraja, god-kings whose sacred power was associated with the Hindu, gods Indra and Vishnu. To many Western observers, the kings of Ayutthaya were treated as if they were gods. The French Abbe de Choisy, who came to Ayutthaya in 1685, wrote that "the king has absolute power. He is truly the god of the Siamese: no one dares to utter his name." Another 17th-century writer, the Dutchman Van Vliet, remarked that the king of Siam was "honored and worshipped by his subjects more than a god.

The Ayutthaya period was early Thai history's great era of international trade. Ayutthaya's role as a port made it one of Southeast Asia's richest emporia. The port of Ayutthaya was an entrepot, an international marketplace where goods from the Far East could be bought or bartered in exchange for merchandise from the Malay/Indonesian Archipelago, India, or Persia, not to mention local wares or produce from Ayutthaya's vast hinterland. The trading world of the Indian Ocean was accessible to Ayutthaya through its possession, for much of its 417-year history, of the seaport of Mergui on the Bay of Bengal. This port in Tenasserim province was linked to the capital by a wild but ancient and frequently used overland trade route.
Throughout its long history, Ayutthaya had a thriving commerce in "forest produce", principally sapanwood (a wood which produces reddish dye), eaglewood (an aromatic wood), benzoin (a type of incense), gum lac (used as wax), and deer hides (much in demand in Japan). Elephant teeth and rhinoceros horns were also highly valued exports, but the former was a strict royal monopoly and the latter relatively rare, especially compared with deer hides. Ayutthaya also sold provisions such as rice and dried fish to other Southeast Asian states. The range of minerals found in the kingdom was limited, but tin from Phuket ("Junkceylon") and Nakhon Si Thammarat ("Ligor") was much sought after by both Asian and European traders.
The Chinese, with their large and versatile junks, were the traders who had the most regular and sustained contact with Ayutthaya. The Ayutthaya kings, to conduct a steady and profitable trade with Ming and Manchu China, from the 14th to the 18th centuries, entered willingly into a tributary relationship with the Chinese emperors. The Thais recognized Chinese suzerainty and China's preeminent position in Asia in return for Chinese political sanction and, even more desirable, Chinese luxury goods. Muslim merchants came from India and further West to sell their highly-prized clothes both to Thais and to other foreign traders. So dominant were Chinese and Muslim merchants in Ayutthaya that an old Thai law dating back to the 15th century divides the Thai king's foreign trade department into two: a Chinese section and a Muslim section. Chinese, Indians, and later on Japanese and Persians all settled in Ayutthaya, the Thai kings welcoming their presence and granting them complete freedom of worship. Several of these foreigners became important court officials. 
                                       Containing merchandise from all corners of Asia, the thriving markets of Ayutthaya attracted traders from Europe. The Portuguese were the first to arrive, in 1511, at the time when Albuquerque was attempting to conquer Melaka (Malacca). They concluded their first treaty with Ayutthaya in 1516, receiving permission to settle in Ayutthaya and other Thai ports in return for supplying guns and ammunition to the Thai king. Portugal's powerful neighbor Spain was the next European nation to arrive in Ayutthaya, towards the end of the 16th century. The early 17th century saw the arrival of two northern European East India Companies: The Dutch (V.O.C) and the British. The Dutch East India Company played a vital role in Ayutthaya's foreign trade from 1605 until 1765, succeeding in obtaining from the Thai kings a deer hide export monopoly as well as one of all the tin sold at Nakhon Si Thammarat. The Dutch sold Thai sapanwood and deer hides for good profits in Japan during Japan's exclusion period, after 1635.
The French first arrived in 1662, during the reign of Ayutthaya's most outward-looking and cosmopolitan ruler, King Narai (1656-1688). French missionaries and merchants came to the capital, and during the 1680s splendid embassies were exchanged between King Narai and King Louis XIV. The French tried to convert King Narai to Christianity and also attempted to gain a foothold in the Thai kingdom when, in 1687, they sent troops to garrison Bangkok and Mergui. When a succession conflict broke out in 1688 an anti-French official seized power, drove out the French garrisons, and executed King Narai's Greek favorite Constantine Phaulkon, who had been championing the French cause. After 1688, Ayutthaya had less contact with Western nations, but there was no policy of national exclusion. Indeed, there was increased trading contact with China after 1683, and there was continued trade with the Dutch, the Indians, and various neighboring countries.
Ayutthaya's relations with its neighbors were not always cordial. Wars were fought against Cambodia, Lanna, Lanchang (Laos), Pattani, and above all, Burma, Ayutthaya's powerful neighbor to the west. Burmese power waxed and waned in cycles according to their administrative efficiency in the control of manpower. Whenever Burma was in an expansionist phase, Ayutthaya suffered. In 1569, King Bayinnaung captured Ayutthaya, thus initiating over a decade's subjection to the Burmese. One of the greatest Thai military leaders, Prince (later King) Naresuan, then emerged to declare Ayutthaya's independence and to defeat the Burmese in several battles and skirmishes, culminating in the victory of Nong Sarai, when he killed the Burmese Crown Prince in combat on elephant back.
During the 18th century, Burma again adopted an expansionist policy. The kings of the Alaunghphaya Dynasty were intent on subduing the Ayutthaya kingdom, then in its cultural and artistic prime. The Burmese invaded Ayutthaya in 1765. This time Burmese caused much fear to Thais. Burmese soldiers destroyed everything, including temples, manuscripts, and religious sculptures. After the capital fell into their hands for two years, the Burmese effectiveness could not further hold the kingdom. Phaya Taksin, a Thai general, promoted himself to king in 1769. He ruled the new capital of Thonburi on the bank of the Chao Phraya River, opposite Bangkok. Thais regained control of their country and thus scattered themselves to the provinces in the north and central parts of Thailand. Taksin eventually turn himself to be the next Buddha and was dismissed and executed by his ministers who did not approve of his religious values.

Chao Phraya Basin under the Tai

There are several legends about the Tai coming to rule mandalas of Central Thailand including Lavo and Suphannabhum. The Suphannabhum mandala had been independent of Khmer influence and composed originally of the Western Provinces of modern Thailand including Suphanburi, Ratchaburi, and Phetchaburi. In the 12th century, the Tai Po Khuns of the upper Chao Phraya coalesced around the Po Khun of Sukhothai - an important Khmer outpost. With the weakened Khmer authority, Po Khun Si Nau Namthom
of Sukhothai gained the autonomy of the upper Chao Phraya valley. However, during the reign of Jayavarman VII, the Khmer power was strengthened, and the Tai Po Khuns were subdued and brought under Khmer suzerainty. Suphannabhum was also weakened by Khmer invasions and only the city of Suphanburi itself was left.

Sukhothai and Lanna

Thai city-states gradually became independent from the weaker Khmer Empire. It is said that Sukhothai was established as a sovereign, strong kingdom by Pho Khun Si Indrathit in 1238 AD. A political feature called by 'classic' Thai historians as 'father governs children' existed at this time. Everybody could bring their problems to the king directly as there was a bell in front of the palace for this purpose. The city briefly dominated the area under King Ramkhamhaeng, who established the Thai alphabet, but after he died in 1365 it fell into decline and became subject to another emerging Thai state: the Ayutthaya kingdom in the lower Chao Phraya area.
Another Thai state that coexisted with Sukhothai was the northern state of Lanna, centered in Chiang Mai. King Phya Mangrai was its founder. This city-state emerged in the same period as Sukhothai. Evidently, Lanna became closely allied with Sukhothai. After the Ayutthaya kingdom had emerged and expanded its influence from the Chao Phraya valley, Sukhothai was finally subdued. Fierce battles between Lanna and Ayutthaya also constantly took place and Chiang Mai was eventually subjugated, becoming Ayutthaya's 'vassal'.
Lanna's independent history ended in 1558 when it finally fell to the Burmese; thereafter it was dominated by Burma until the late 18th century. Local leaders then rose up against the Burmese with the help of the rising Thai kingdom of Thonburi of King Taksin. The 'Northern City-States' then became vassals of the lower Thai kingdoms of Thonburi and Bangkok. In the early 20th century, they were annexed and became part of modern Siam, the country now called Thailand.

Hariphunchai

According to the Jamadevivamsa, the city of Hariphunchai (modern Lamphun) was founded by the hermits; Jamadevi, a Lavo princess, was invited to rule the city in around 700 AD. However, the date is considered too early for the foundation of Hariphunchai as Jamadevi brought no Thammachakras to the north. Hariphunchai may be a later (about the 10th century) offshoot of the Lavo kingdom or instead related to the Thaton kingdom.
Hariphunchai was the center of Theravada in the north. The kingdom flourished during the reign of King Attayawong who built the Dhatu of Hariphunchai in 1108. The kingdom had strong relations to another Mon kingdom of Thaton. During the 11th century, Hariphunchai waged lengthy wars with the Tai Ngoenyang kingdom of Chiang Saen. Weakened by Tai invasions, Hariphunchai eventually fell in 1293 to Mangrai the Great, king of Lanna, the successor state of the Ngoenyang kingdom

Si Kottaboon

While the Dvaravatians ruled Chao Phraya, Isan was the place of the Si Kottaboon culture, which belonged to the native Mon-Khmer people. Si Kottaboon is regarded as a stem culture of Dvaravati with Mon scripts and oval-shaped cities. The Thammachakras of Dvaravati became the Semas or Stone Leaves of Si Kottaboon. The culture tolerated the Khmer Chenla expansions around the 7th century. The southeasternmost part of Isan was the heartland of the Chenla kingdom that expanded over the southern Funan around the 7th century

Dvaravati

The Chao Phraya valley in what is now Central Thailand had once been the home of Mon Dvaravati culture, which prevailed from the 7th century to the 10th century. The existence of the civilizations had long been forgotten by the Thai when Samuel Beal discovered the polity among the Chinese writings on Southeast Asia as “Tou-lo-po-ti”. During the early 20th century the archeologists led by George Coedès made grand excavations on what is now Nakorn Pathom and found it to be a center of Dvaravati culture. The constructed name Dvaravati was confirmed by a Sanskrit plate inscription containing the name “Dvaravati”.
Later on, many more Dvaravati sites were discovered throughout the Chao Phraya valley. The two most important sites were Nakorn Pathom and Uthong (in the present Suphanburi Province). The inscriptions of Dvaravati were in Sanskrit and Mon using the script derived from the Pallava script of the Pallava dynasty. The religion of Dvaravati is
thought to be Theravada through contacts with Sri Lanka, with the ruling class also participating in Hindu rites. The Dvaravati art, including the Buddha sculptures and stupas, showed strong similarities to those of the Gupta dynasty. The most prominent production of Dvaravati art are the Thammachakras or the Stone Wheels signifying Buddhist principles. The eastern parts of the Chao Phraya valley were subjected to a more Khmer and Hindu influence as the inscriptions are found in Khmer and Sanskrit.

Dvaravati was not a kingdom but a network of city-states paying tributes to more powerful ones according to the mandala model. Dvaravati culture expanded into Isan as well as southwards as far as the Isthmus of Kra. Dvaravati was a part of ancient international trade as Roman artifacts were also found and Dvaravati tributes to the Tang court are recorded. The culture came to an end around the 10th century when it was replaced by a more unified Lavo-Khmer polity.