The North food

Thailand as a kingdom first began to take shape in the mountainous North, with a number of city states that eventually became a loose federation known as lanna, centred around Chiang Mai. Later, the Thais migrated southwards and Sukhothai became the first true capital of Siam. After, Sukhothai came Ayutthaya, even further to the south; and then, of course, Bangkok. The romoteness of the North meant that it functioned more as a vassal state than as and integral part of the country, and consequently kept its own traditions, language, dress, architecture and food. Because of the cooler mountain climate, there is a lager variety of vegetables than in other regional Thai cuisines, and roots and herbs have a strong presence. There are many sour and bitter flavoures, especially apparent in the soups, such as Kaeng ho, a soup made with pickled bamboo shoot.The Influence of neighboring Mynmar and Laos is a strong one in the cuisine. People of the North prefer glutinous rice to white rice, rolling it into balls with their hands, and dipping into dishes and sauces. Somtam, the spicy green papaya salad highly popular in the Northest, is also a familiar dish in the North.Form Myanmar come Khao soi, a curry broth with egg noodles and chicken pork or beef; and kaeng hang lay, a pork curry seasoned with ginger, tamarind and turmeric. curries are thinner in this region with the two most popular curry dishes being Kaeng yuak, made with banana palm hearts; and kaeng Khanoon, made form the aromatic jackfruit.Sausages are a speciality. The best known is sai ua, which blends aground pork with dried chillies, garlic, shallots and lemon-grass to produce a spicy red sausage. There is also a sausage called naem maw, prepared in a clay pot with ground pork, pork rind and sticky rice, plus garlic and chilli. This is eaten uncooked, the mixture having fermented to create a strong sour taste.The North is noodle heaven, the ethnic mix of Yunnanese, Shan and Burmese having produced a seemingly endless range of kuay tiaw and khanom chin dishes. In Chiang Mai, the khao soy egg noodles eaten with chicken or beef curry and number of spicy and sour side dishes were brought in by the caravans of Yunnan Moslems. Wunsen noodles are another Chinese import; made form mung bean starch, they are a part of curries, soups and stir-fires. Khanom chin nam ngiew is soft thin rice noodles with pork rib, tomatoes and back bean sauce.
No visit to the North is complete without sampling a Khan toke dinner. The name derives form a khan, or bowl, and a toke, a low round table made of woven bamboo, plain of lacquered. Guests sit on the floor, usually watching a cultural performance, and serve themselves form the assorted dishes of northern specialities placed on the table.

Reference http://www.sawadee.com/thailand/food/regional.htm