Thai's of earlier times, like their descendants today, placed enormous importance on the rituals and politeness of eating. This concern was shown in the way they greeted each other informally. If they saw a friend passing their home, they would immediately ask: "Have you eaten yet?" This not just out of politeness. If the answer was no, the friend would be invited in, and something would be prepared to eat right then and there.

Most of the dishes people cooked in those days were simple to make, using ingredients that could be found nearby. In the kitchen there would be chili, shrimp paste, fish sauce, sour tamarind, garlic, shallots, and dried fish.
Fresh indigenous Thai vegetables like phak bung, phak krachet, krathin and bamboo shoots could be found growing almost anywhere. A meal made up of nam phrik kapi (chili paste), grilled fish, boiled phak bung leaves, and perhaps a hot kaeng som curry could be prepared in just half an hour or so.

Traditionally, Thai food used commonly found plants and meats as ingredients. Fish was by far the most widely used meat, as it was available in all seasons, wet or dry. In the rainy season, when the rivers and canals were full, there were obviously plenty of local fresh-water fish. Even when the weather turned dry and hot, there were still catfish, snake-heads and other species to be found in ponds and lakes. Some were cooked, others were stored. Small fish would be fermented to make pla ra and fish sauce to be kept for future use. Larger ones would be salted.

Chicken, duck, and pork were eaten only on special occasions. Beef and the meat of the water buffalo were not eaten by Thais of earlier eras, as they revered the animals as man's helpers in the fields.

Vegetables consisted of local edible plants, of which there were many; Thai cooks used a total of 255 species. These fell into five categories: leaf plants, root plants, edible flowers, seed pods, and fruiting plants. Most of these plants appeared only in a certain season. Therefore, in every part of Thailand, the foods people ate would change as the months passed.

But there was more to preparing these Thai dishes than just gathering some local plants and meats and throwing them into a pot. Flavors had to be balanced and blended. Nam phrik kapi, the most popular of the Thai repertoire of chili sauces, combines heat from chilies, sweetness, and saltiness. To create a proper balance of flavors, small, pea-sized eggplants called makhuea phuang are added to give it a needed bitter tang. If they are left out, the dish loses its characteristic taste and no longer qualifies as nam phrik.

Dishes eaten during the winter, such as the soup-like kaeng liang made from gourds or other bland vegetables, need the heat of peppercorns and shallots, as well as the fragrant leaf of the basil plant to make them savory and appetizing.

Kaeng som, a soup-like dish that combines sourness and sweetness, comes close to being a Thai "national dish", as variants of it are eaten in all regions of the country. In the Central Plains and the North, tamarind (makham piak) is used to give it its sour bite. North easterners use the acid leaves of the okra plant (called bai phodi or "just-enough leaves" in Thai because no matter how many of them are added, the sourness is somehow always just right). In the South, if there is no sour tamarind available, another type called makham khaek is substituted.

Kathi, or coconut cream, is common in Thai cooking. In earlier times, however, it was not used at all. When curries that make use of it like kaeng kari and kaeng massaman were imported from India, they brought the use of coconut cream and their characteristic spices with them. Eventually, the creamy extract of coconut meat had found a central place in recipes that we today consider completely Thai, such as kaeng khiao wan, the spicy curry that is so popular everywhere.

Sweets that make use of coconut cream were also introduced from India. Custard-like khanom mo kaeng is an example. The original version from India used flour, sugar, and milk, but milk was scarce at the time when it found its way into Thai kitchens, so cooks used coconut cream instead.

Fried foods also came from abroad, but their place of origin was China. The iron frying utensils called katha in Thai originally had to be imported from China, and the technique of cooking using hot oil came together with the introduction of Chinese vegetables that taste best when prepared that way, such as Chinese broccoli and Chinese radish.

Noodle dishes like the kuai tiao soup sold on street stalls everywhere also originated in China. Those found in Thailand have been given a strong Thai character. The best known is kuai tiao phad Thai, the "Thai fry" which has made a reputation for itself all over the world.

The original Thai style ice cream was sold from little boats that were paddled along the city's canals. Its main ingredient was coconut cream, but not the extremely thick and heavy kind. It was not especially sweet, either. The ice cream was stirred and chilled until it was of a runny, slushy consistency, rather than hardened to the point where it could be formed into scoops, as it is today.

Ice cream is not alone in having been adapted and altered under the influence of new or imported trends and techniques. Centuries ago, food prepared for the royal court was the product of extremely elaborate and complex cooking methods. Khao chae, for example, was originally a special dish served to the court on Songkran, the traditional Thai New Year. The most fastidious care was given to selecting every grain of rice to ensure that it was perfect, with no husk adhering to it.

When served in the chilled, scented water that gives this dish its unique character, it is delicious. The various side dishes are easy to prepare :fried and shredded salted beef, fried leaf vegetables, Chinese radish, and other simple things. But as served in the palace, these side dishes were delicacies whose preparation required the highest artistry. Fresh vegetables served with the royal khao chae were carved, for example, often to form ornamental sculptures of fantastic delicacy. Such items were part of a special culinary repertoire known as Royal Cuisine.

Today, the original range of Thai dishes has spread out to include many imports and innovations, while the old recipes they are based upon become increasingly hard to find. The sour-salty-hot salad known as yam was once almost exclusively a vegetable dish. But as time went on, approaches to the dish diversified. Glass noodles are now commonly added.

Vegetables used in making these evolving dishes permitted new shades of variety. As one type went out of season, another would appear and be experimentally substituted, leading to tasty new discoveries. Old-fashioned kaeng liang nam tao, a kind of traditional vegetable soup made with green gourds, tasted fine when made with local pumpkin. As new vegetables from abroad appeared in the markets, it was found that interesting versions could be made from baby corn or shredded carrots. But with these additions came depletion's. Few among the new generation of cooks, for example, knows how to use bai maeng lak, one of the fragrant types of basil that lent its distinctive aroma to so many of the dishes relished by Thai's of earlier eras.

Food is like music created through the ages to give pleasure, down to the latest generation with its contemporary tastes. Today, many more people buy the food they eat than cook it themselves. A wide variety of commercially prepared foods is therefore available to keep everyone happy. If a food shop offers cooking that people don't like, it won't last long, but on the other hand, the more new and exciting recipes a commercial cook can devise, the more people he or she will attract.

Therefore, the art of cooking as it is today doesn't really differ that much from what it was in the old days. It is an organic, growing tradition that continues to recruit the ingredients at hand to produce its distinctive, unmistakably Thai creations.