The Hill Wars
With the fall of Chiang Mai, Ayudhya distroyed the power base of the Lan Na kingdom. However further to the north in Fang province Sam Fang Kean has declared himself king of Lan Na, where he is joined by the provinces of Chiang Saen and Phayao. To the north east the provinces of Phrae and Nan look down onto the plain that is the source of much of Ayudhya’s prosperity.
In 1443 and the army of Nan marched south, meeting the army of Ayudhya near the city of Uttaradit, on the North Thai plain. After a brief battle at which the Nan army was routed, Ayudhya began a series of campaigns initially against the state of Nan, but later against the states of Phrae and Luang Prabang. It was during this period that Borommaracha moved his capital to Phitsanulok, appointing has son Ramesuan regent in Ayudhya itself. From his more northerly capital king Borommaracha quickly subdued Nan then Phrae, and began a campaign against their ally Luang Prabang. In 1448 on the banks of the Mekong river near Tha Deua the war reached its climax when King Borommaracha was killed. His death marked an end to the campaigns against the hill kingdoms.
The 12 year old Prince Ramesuan was installed as King Borommatrailokanat (Trailok), and the capital returned to Ayudhya. Under the influence of his advisors, many of whom came from the former Khmer Empire, he began a series of reforms of his government. Delineating the bureaucracy, and defining everyone’s place within society. In effect it allowed Ayudhya to utilise its man power more effectively, allowing more men to be assigned to state projects. At the time all freemen within the kingdom had to give up six months of every year to work on state projects, Trailok’s reforms allowed this servitude to be exploited more effectively.
By 1458 Trailok had proved that his reforms and the campaigns of his father in the north were to give Ayudhya a massive advantage. In 1453 he began a campaign against Tenasserim and by 1458 Ayudhya had managed to secure the important Kra isthmus with the capture of Chumphon. The Kra isthmus had been the source of much of the wealth of the old Sukhothai empire, now Ayudhya could control the portage of goods from one side of the isthmus to the other.
Only one state was more important in controlling trade between east and west, the Sultanate of Malacca. Despite the decline of Chinese interest in the port, it was an extremely important entrepot controlling the valuable trade routes through the straits. If Ayudhya could control Malacca they would control all east west trade.