There are many ethnic groups inhabiting in Thailand, especially in some areas like mountains or forests, including those areas of northern Thailand. In the past, many events, including chaos, happened. There is no wonder why some groups of people had to abandon their hometowns and evacuated to Thailand.
These ethnic groups are mostly friendly. Basically, they originated from nearby countries and have cultures of their owns. If it is possible, you should find yourself a chance and learn about their cultures. It will be your good knowledge and experience.
Of course, the best way to study about ethnic groups is to visit their communities, so that you will see how they live. Reading texts only are not going to help much. And if you don’t know where their communities are, then here are some suggestion for you.