1350 - The leading general of Utong, upon the death of the kingdom’s ruler, becomes King of Utong himself and assumes the title Rama Tibodi I. One of his first decisions is to transfer his capital some 50 kilometers (31mi) to the east, to the thriving trade town of Ayutthaya. (The similarity to the beginning of the Bangkok period in Thai history is striking; 432 years later, it is again the leading general of a preceding king who becomes king; at both instances, one of their first tasks is to transfer their capitals; contrary to what is often read in English language guide books, both towns, Ayutthaya and Bangkok, are not "founded" by the two kings but were already well established settlements, though with no political functions.)
1350-1359 - King Rama Tibodi I introduces coded laws.
1352 - Ayutthaya engages Cambodia in war. Cambodia is seized and its ruler, King Pasat, becomes the vassal of Siam. Even though its the Khmers (or Cambodians) who are defeated in this war, it’s rather Khmer culture that penetrates Thai society in the following decades and centuries than Thai culture penetrating Khmer society. One example is that Siam adopts the Khmer system of slavery as well as the concept of absolute monarchy.
1357 - Cholera spreads in the kingdom of Siam and claims, among thousands of others, the lives of two of its princes, Chaokeo and Chaotai.
1361 - King Rama Tibodi I becomes a Buddhist priest.
1369 - King Rama Tibodi I dies aged 57, and his son, Prince Ramesuan, succeeds on the throne. Incompetence displayed during the Cambodian war makes him unpopular among his people.
1370 - Upon public clamor and advice of his ministers, Prince Ramesuan abdicates his throne in favor of his uncle, Prince Boromaraja (the brother-in-law of King Rama Tibodi).
1371 - King Boromaraja begins invading Sukhothai, capturing several towns.
1375 - Phitsanulok, the substitute capital of Sukhothai, is taken by Boromaraja’s forces and prisoners are turned into slaves.
1378 - King Tammaraja II of Sukhothai is forced to become a vassal of the King of Ayutthaya. This marks the end of the independent Thai Kingdom of Sukhothai after 140 years of existence.
1388 - King Boromaraja dies and his son Tonglan, 15 years old, succeeds the throne. 7 days thereafter, the former King of Ayutthaya, Ramesuan, seizes the young king, most probably has him killed and assumes the throne.
1390 - Senmuangma, the young king of Chiang Mai (Lannatai Kingdom), attempts to overthrow the Ayutthaya Kingdom and to regain Sukhothai for its King Tammaraja II but the Chiang Mai army is defeated by the Ayutthaya forces. King Ramesuan succeeds in invading Chiang Mai and resettles parts of the city’s population to other areas held by Siam (Ayutthaya), some as far south as the Malayan Peninsula. Though the people of Chiang Mai are ethnically Thais, they have at that time a dialect quite different from the one spoken in Siam, having migrated from what is now Yunnan in southern China several centuries later than the Thais settling further south.
1393 - War breaks out again with Cambodia provoked by the Cambodian King Kodombong who captures Chonburi and Chantaburi taking much of the population of the two towns back to Cambodia. King Ramesuan, upon learning of the event, sends his troops to Cambodia, invades Angkor and takes almost 90,000 Cambodians as prisoners to Siam, leaving the Khmer kingdom again as vassal of Siam. The year 1393 thereby established a pattern that will be much adhered to in southeast Asia for centuries to come. Victorious kings and generals are not content with ransacking the towns of defeated neighbors and imposing tributes. As the constant wars between Thais, Burmese and Khmers take heavy tolls on the populations of the kingdoms, gaining new subjects to replace those killed in battle becomes an objective of war. To judge such a population policy it has to be noted that the wars between the three nations have often been total wars. Occasionally, most of the men of a kingdom were conscripted, from ages today considered as childhood. Furthermore, women have also regularly fought in battles. The population policy of capturing subjects has also contributed to the ethnic mix found now in southeast Asia. Racial descent is an insufficient criterion to differentiate Thais, Mons, Khmers, Shans etc. Rather, it’s language and regional culture that make the difference.
