1282 - How Chow Chi, a Chinese Mandarin comes to Sukhothai and negotiates a treaty of amity between China and Sukhothai.
1283 - King Mengrai of Lannatai conquers the Mon Kingdom of Haripungaya (present-day Lamphun), making it a long lasting part of his realm. Later kingdoms of the Mons will all be located at the western side of the mountain range that today separates the territories of Burma and Thailand.
1300 - Death of Ramkhamhaeng; the throne is ascended by his son, Loetai. Sukhothai begins its decline. In the following years, most of the non-Thai principalities ruled by King Ramkhamhaeng and many of the Thai principalities as well become rather independent from Sukhothai.
1338 - The major Thai principality of Phayao east of Chiang Mai is annexed to the Lannatai Kingdom.
1330-1350 - The principality of Utong (near today’s town of Suphanburi, close to Ayutthaya, becomes a regional power, largely due to the military skills of its leading general. A personal name of this general is not known. (It must be noted here that in Thai or Siamese tradition, personal names have much less bearing than in the western culture. Typically, a man changed his name when he assumed additional power, either by being promoted or by usurping it. Many of the names under which important Thai or Siamese personalities are known in history are anyhow rather titles than names. One important example of later times is the designations Chao Phaya. Chao Phaya, aside from being the name of the main Thai river, is a Thai title, designating the highest government officials; typically the leading general of a principality was named Chao Phaya - as for example several hundred years later Chao Phaya Chakri, the founder of the current Thai dynasty who had first been the leading general of King Taksin of Thonburi). The leading general of Utong (who didn’t bear the title Chao Phaya during his life-time but would later be designated as such) gains for his principality several adjourning areas which have so far been ruled by the king of Sukhothai. He is the initiator of the Ayutthaya period of Thai history.
1347 - Prince Lutai (Tammaraja I), a son of King Loetai, becomes King of Sukhothai. It is not known how long Sukhothai was ruled by King Loetai. The accepted theory is that after King Loetai died, there was heavy competition for the throne; most probably a king with the name Nguanamthom ruled for a period of time between the reigns of Loetai and Lutai Tammaraja I. King Lutai concentrates rather on religious than political matters, a fact further contributing to the loss of political power of Sukhothai. Tammaraja, a name he acquires posthumously, is a religious rather than political title.
1370 - King Lutai dies and is succeeded by his son Prince Sai who becomes King Tammaraja II.
1371 - King Boromaraja I of Ayutthaya invades Sukhothai territory, 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 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.
