Before we get into the answer, it’s useful to consider two points:

First of all, trade in the region was more of a web than a single route. Plenty of small boats made short to medium trips between ports within Southeast Asia, rather than going all the way to China or India. A trader might shuttle between Surabaya, Banten and Ayuttaya, for example. Ayutthaya didn’t have to be the equivalent of a rest stop along a highway, it could be an attractive destination in itself.

Secondly, we must view the port cities of Southeast Asia not as passive entities that waited for the money to start rolling in, but as the capitals of states. They had a wide range of tools at their disposal, such as diplomatic marriages and warfare, that they had to actively use to maintain their status. Competition was fierce, and location, while important, was not enough to guarantee success.

With that in mind, there are several areas in which Ayutthaya used the tools at its disposal to thrive as a commercial centre within this web of commerce:

Ayutthaya as China’s preferred trading partner

From 1371, the newly established Ming Dynasty banned private trade and funnelled all foreign trade through the tribute system. Only tribute missions were allowed to trade, under strict conditions. A tribute mission would bring cargo, officially registered as “gifts”. In return, China would reciprocate with gifts of its own, such as silks, porcelain and medicine.

Over the next century or so, Ayutthaya skillfully exploited these arrangements to become the Ming Dynasty’s preferred trading partner. It clearly knew what the emperor and China’s luxury market desired - the Ming shi-lu (Ming Histories) lists 44 “customary trading articles” from Ayutthaya, more than for any other port, including aromatics, textiles, pepper, black bears, white monkeys, elephants and a six-legged tortoise. Damaged Ayutthayan ships were repaired or replaced in Chinese ports, sending extra business their way.

Between 1369 and 1439, Siam sent 68 tribute missions to China, more than any other port. This was roughly 3 times more frequently than the Chinese stipulation of 1 every 3 years.

So indispensable was Ayutthaya that its traders were also able to quietly work outside official lines, with private traders, and suffer nothing more than mild rebuke when caught. And the Ming shi-lu mentions that in 1480 the emperor sent the Ayutthayan ruler a set of red-dragon robes, which historian Geoff Wade notes as being “very unusual in Ming foreign relations and suggests a relationhip of some closeness”.

This relationship had 2 effects on Ayutthaya.

First, in order to secure sources of exotic goods to send as tribute, Ayutthaya needed to “develop” its hinterland. Between 1370 and the early 1500s, Ayutthaya attacked the land-based polities around it, seizing manpower and demanding tribute. Thereafter, valuable goods could flow into Ayutthaya from its hinterland before being shipped out to China.

Aromatic wood such as eaglewood, sappanwood, from which dyes were made, deerskins, elephants, and ivory started arriving in Ayutthaya. From Laos came gold and benzoin, another aromatic compound. The Gulf of Siam supplied stingray skins and tin flowed from the mines in Phuket.

Ayutthaya’s position at the confluence of 3 rivers made transportation of these goods relatively easy. Access to the Lopburi and Pa Sak rivers more than made up for whatever minor inconvenience there was in sailing down the wide, navigable Chao Praya. Indeed, Ayutthaya’s rulers continued to develop the Chao Praya, digging canals and straightening out its bends to make things even easier. The 3 waterways effectively gave Ayutthaya access to local, regional and international trade.

Developing the links between the hinterland and Ayutthaya also had an effect on its trade with its neighbours, as surplus goods could now be traded with other polities. The Dutch, for example, bought large quantities of deerskins. Foodstuff like rice, salted fish, arak and vegetables, which the Chinese court usually placed no great importance on, found a ready market in Melaka, and could be traded for spices, opium and slaves.

The second effect of Ayutthaya’s relationship with China rested on the private, technically illegal trade with Chinese merchants. By the 1490s, this trade was outstripping the official tribute trade. Chinese merchants found Ayutthaya to be an excellent entrepot port.

By this time, Ayutthaya controlled not just vast tracts of land to its north, but also land all the way to the west coast of the Malay Peninsula. Ports such as Tenasserim, Mergui, Kedah and Selangor were its vassals. Chinese merchants found a ready market for their goods in Ayutthaya. These were then transported overland to the abovementioned ports where they were shipped westwards to the Indian ocean and beyond. And, of course, goods flowed the opposite way as well, allowing Chinese merchants to bounce between Ayutthaya and China.

This trade increased after the Portuguese conquered Melaka in 1511. Occasional attacks from the heir to the Malaccan Sultanate and the Sultanate of Aceh, and disillusionment with Potuguese policies, drove traders to look for alternatives. When conditions in the strait were messy, traders found the land route to Ayutthaya a decent alternative.

(Continued in reply)