Today, hill farmers in Northern Thailand mainly grow cash crops such as rubber. In the past, however, many practiced swidden farming, which involved burning off forest to plant a wide variety of crops, then rotating to new forest lands after several years, when the current fields had been exhausted. According to anthropologists who have studied this, there were three main types of swiddening, which is also known as slash-and-burn farming or shifting cultivation. The first can be termed “integral” or “cyclical” swiddening (raj muunwian in Thai.) Here the village controlled how much land each family could cultivate. The system was stable and the villagers did not need to move or acquire new land. The second type, practiced by ethnic groups like the Hmong, was “pioneer” swiddening (raj luanlooj in Thai.) Here, individual families would cultivate as much land as they could manage, and after using it intensively would move to a new area with virgin forests. There was also a third type of swiddening, practiced mainly by ethnic Thai lowland farmers. These people were “partial” swiddeners, who cultivated hill land in addition to their paddy fields, because population growth had left little available land elsewhere.