Early years
The Thais, most historians believe, began migrating from southern China in the early part of the Christian era. At first they formed a number of city-states in the northern part of what is present-day Thailand, in places like Chiang Saen, Chiang Rai and Chiang Mai, but these were never strong enough to exert much influence outside the immediate region. Gradually the Thais migrated further south to the broad and fertile central plains, and expanded their dominance over nearly the entire Indochina Peninsula. Contradictory as it may seem, however, recent archaeological discoveries around the northeast hamlet of Ban Chiang suggest that the world's oldest Bronze Age civilization was flourishing in Thailand some 5,000 years ago.

Sukhothai Period(1238-1438) Sukhothai was the first Thai kingdom. It was founded in 1238 by two Thai governors, Khun Bang Klang Thao (Sri Inthrathit) and Khun Pha Muang who rebelled against the Khmers; and gave independence to the region. Sukhothai period was the most flourishing period of Thailand. It gained independence in 1238 and quickly expanded its boundary of influence. Sukhothai period was considered to be a golden age of Thai culture.		During that time in the history, everybody could say that "There are fish in the water and rice in the fields". The boundary of Sukhothai stretched from Lampang in the north to Vientiane, in present day Laos and the south to the Malay Peninsula. During this time Thai had strong friendship with neighboring countries. It absorbed elements of various civilizations which they came into contact. Thai maintained and advanced their culture with China. The potters entered Thai artistry and extensive trade was established with Cambodia and India.
After the death of Khun Pha Muang in 1279, Ramkhamhaeng King, the third son of Si Inthrahit, ascended to the throne. Under the Ramkhamhaeng King, Sukhothai had strong friendship with neighboring China. Ramkhamhaeng King organized a writing system which became the basis for writing and eventually developed to be the modern Thai alphabet.

Ayutthaya Period(1351-1767) Ayutthaya, the capital of the Thai Kingdom was found 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 Loburi and surrounded by rice terraces. It is easy to see why the Ayutthaya area was settled prior to this date since the site offered a variety of geographical and economic advantages. The Thai kings of Ayutthaya became powerful in the 14th and 15th centuries, taking over U-Thong, Lopburi, and Ayutthaya. 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 government could not remain the same as during the days of King Ramkhamhaeng. The society during the Ayutthaya period was strictly hierarchical. There were, roughly, three classes of people king at the top of scale. At the bottom of social scale were commoners and the slaves.
In the early 16th century, the European visited Ayutthaya, and a Portuguese embassy was established in 1511. Portugal's powerful neighbor Spain was the next European nation to arrive in Ayutthaya forward the end of the 16th century. In he early 17th century they saw the arrival of two northern European, the Dutch and the British, and France in 1662. In the mid-16th century, Ayutthaya and the independent kingdom in Chiang Mai was put under the control of the Burmese, but Thais could regain both of the capitals by the end of the century. The Burmese invaded Ayutthaya again in 1765. This time Burmese caused much fear to Thais. Burmase soldiers destroyed everything, including temples, manuscripts, and religious sculpture. After the capital fell in their hands for two years, the Burmese effectiveness could not further hold the kingdom. Phaya Taksin, a Thai general, promoted himself to be the king in 1769. He ruled the new capital of Thonburi on the bank of Chao Phraya River, opposite Bangkok. Thais regained control of their country and thus scattered themselves to the provinces in the north and central part of Thailand. Taksin eventually turn himself to be the next Buddha and was dismissed and executed by his ministers who did not approve his religious values.

Thonburi Period(1767-1782)
After the fall of Ayudthaya, General Taksin, a general of Aydthaya, drafted an army of patriots to take revenge for his country. He successfully chased away the Burmese troops. After the Burmese were gone, he decided to build a new capital along the Chaopraya river and named it "Thonburi". King Taksin has reined a peaceful country for over 15 years and extended diplomatic relationship with many countries from overseas including China. Unfortunately, King Taksin, who devoted his life to protect his beloved country, was over stressed from the wars and eventually became insane. Thonburi was collapsed because of the coup in 1782 by General Chakri. King Taksin's achievements have caused prosperity to bestow on him the epithet "the Great"

Rattanakosin Period (1782-Present) After Taksin's death, General Chakri became the first king of the Chakri dynasty, Rama I, ruling from 1782 to 1809. His first action as king was to transfer the royal capital across the river from Thonburi to Bangkok and build the Grand Palace. Rama II (1809-1824) continued the restoration begun by his predecessor.		King Nang Klao, Rama III (1824-1851) reopened relations with western nations and developed trade with China. King Mongkut, Rama IV, (1851-1868) of "The King and I" concluded treaties with European countries, avoided colonialization and established modern Thailand. He made many social and economic reforms during his reign.
King Chulalongkorn, Rama V (1869-1910) continued his father's tradition of reform, abolishing slavery and improving the public welfare and administrative system. Compulsory education and other educational reforms were introduced by King Vajiravudh, Rama VI (1910-1925). During the reign of King Prajadhipok, (1925-1935), Thailand changed from an absolute monarchy to a constitutional monarchy. The king abdicated in 1933 and was succeeded by his nephew, King Ananda Mahidol (1935-1946). The country's name was changed from Siam to Thailand with the advent of democratic government in 1939.

From absolute monarchy to constitutional monarchy The politics of Thailand took some significant turn on 24 June 1932 when a group of young intellectuals, educated abroad and imbued with the concept of Western democracy, staged a bloodless coup, demanding a change form absolute to a constitutional monarchy, Determined to avoid any bloodshed, His Majesty King Prajadhipok (Rama VII) agreed to the abolition of absolute monarchy and the transfer of power to the constitution-based system of government as demanded.
To some, this demand was premature, but fortunately with the far-sightedness of King Prajadhipok and his predecessors in particular King Chulalongkorn the Great (Rama V) and King Vajiravudh (Rama VGI), Thailand was not unprepared for this transition. While continuing the process launched by the two previous kings, King Prajadhipok had every intention of accustoming the Thais to the Western system of constitutional monarchy and had considered the eventuality of altering such form of government to the people at an appropriate moment. Popular readiness, the King believed, was an important Ingredient to success for such transition. It was only a matter of waiting for the right time.
On 10 December 1932, His Majesty King Prajadhipok signed Thailand first constitution and thus ended 700 years of Thailand absolute monarchy. Despite the number of successive constitutions that followed in the span of just over half a century, the basic concepts of constitutional government and monarchy laid down in the 1932 constitution have remained unaltered.