With Ayutthaya laid out around the rivers, with canals connecting different areas, much of the city's business took place on water. This included not just the trade, but also the daily activities – like meals. During the years of the Ayutthaya Kingdom, vendors would cook noodles on board small boats and sell them to people on shore or on other vessels. This was the genesis of one of Ayutthaya's best-known dishes – now simply called 'boat noodles.
The soup's broth is made with dark soy sauce, herbs, spices, and cow's blood (which works as a natural thickener, as well as adding flavour). It is usually served with pork or beef, along with meatballs. The portions are small and that's for two main reasons. Firstly, it was often eaten as a snack, with hungry patrons just ordering more bowls if they wanted a full meal. And, secondly, it was easier to serve small bowls from a boat, with less chance of anything spilling as it was handed over the side.
These days, boat noodles are still one of the most popular dishes in Ayutthaya, although they are now served in restaurants, rather than from the canals. Many of these shops still have a replica of a boat and try to give a sense of how the food was traditionally prepared. You can order the noodles with or without the broth (both options are popular with locals) and they're often eaten with pork crackling.
Although Ayutthaya is credited with creating the idea of boat noodles, the concept has spread across Thailand – particularly to Bangkok, which had its own network of canals that facilitated the traditional style of serving. Over the centuries, little has changed with the dish and it's still a special connection with the history of the old kingdom.