Social and political developments
With abundant of arable land and water – and thus food - the survival and prosperity of the Ayutthaya depended on its ability to raise and control enough labor for farming and military defense. Whereas Sukhothai had grown quickly by making friends and allies, Ayutthaya grew by making enemies and conquering them. After each victory, Ayutthaya carried away a number of conquered people to its own territory, where they were assimilated and added to the labor force.
Every freeman (phrai) was subject to conscription – both for service in the army of the local lord (the nai) for a particular military campaign, and for the corvee (“forced labor” on one of the nai’s public works projects). Every phrai had to register for conscription with the nai. The phrai could, however, also meet this obligation by paying a tax instead. If a phrai hated working under his nai, he could sell himself into slavery to a more benevolent nai, who then paid a fee to the original nai as compensation. As much as one-third of the manpower supply into the nineteenth century was composed of phrai.
Wealth, status, and political influence were interrelated. The king allotted rice fields to governors, military commanders, and court officials in payment for their services, according to the sakdi na system. The number of phrai a nai had under him determined: 1) the size of his allotment of rice fields, 2) his social status, 3) his wealth, and 4) his political power.
At the apex of the hierarchy, the king, who was the realm's largest landholder, also commanded the most phrai, called phrai luang (royal servants). King Trailok fixed the size of the allotments of land and phrai for royal officials at each level in the hierarchy. This determined the country's social structure until the introduction of salaries for government officials in the nineteenth century.
Outside this system to some extent was the Buddhist monkhood, or sangha, which all classes of Siamese men could join, as well as the Chinese. Buddhist monasteries (wats) became the centers of Siamese education and culture.
During this period the Chinese first began to settle in Siam, and soon dominated the country's economy, creating a long-standing social problem. The Chinese were not required to register for conscription, and so were free to move about the kingdom and engage in commerce. By the sixteenth century, the Chinese controlled Siam's domestic trade and had found important places in the civil service and military. Most of these men took Thai wives because few Chinese women would leave China to accompany the men.
Around 1600 AD, determined to prevent the dynastic wars of the past two centuries, King Naresuan set about centralizing the country's administration directly under the royal court at Ayutthaya. He ended the practice of making royal princes semi-autonomous vassal-governors of the provinces. Instead he made the office of provincial governor a temporary post, and appointed court officials to the governorships. These civil-servant governors took their orders from the king, implementing his policies, not theirs. Thereafter royal princes were confined to Ayutthaya, where the king could keep a close watch on them.
In order to ensure his control over the new class of governors, Naresuan decreed that all freemen subject to phrai service had become phrai luang, bound directly to the king, who distributed the use of their services to his officials. This gave the king a theoretical monopoly on all manpower, and the idea developed that since the king owned the services of all the people, he also possessed all the land. Ministerial offices and governorships – and the sakdi na that went with them – were usually inherited positions dominated by a few families often connected to the king by marriage.
Even with Naresuan's reforms, the effectiveness of the royal government over the next 150 years should not be overestimated. Royal power outside the crown lands – although in theory absolute – was in practice limited by the looseness of the civil administration. Central government ministers did not have much influence beyond the capital until the late nineteenth century.
Economic Developments
Crown Revenues
During Ayutthaya’s early period, the Crown had five main sources sources of revenue:
Jangkob: revenue from tolls collected from people who used land routes or waterways. The toll rate was either one tenth of the value of the cargo, or a set amount by the size of the boat or wagon.
Akorn: revenue from the sale of permits, licenses, and concessions, and from a general sales tax on all manufactured goods and sevices – but not on agricultural produce such as rice or mangos. (Farmers had to give the Crown a share of their harvest.)
Suay: revenue from tribute paid by vassals and foreign tributaries.
Reucha: revenue from special fees for services given by the Crown, and also half of the amount of any damages awarded the winner in a lawsuit, paid by the loser, also known as “Pinai Luang Money”.
International Trade Revenue came from trading profits and from import and export duties.