In the beginning, during the Sukhothai era, most of the land in Thailand was in the possession of the people, who reserved the right to individually use said land and to transfer it to their heirs. Later, in the Ayutthaya and Rattanakosin eras, the land was owned by the Kings. The people had to request a royal grant in order to obtain land.
At present, the possession of land has to be in accordance with the principle land administration laws. There is the supervising Land Department and some land is still controlled by other governmental authorities, such as the Forestry Department, which is responsible for the management of land in forest zones, while the Sor. Por. Gor. is responsible for land in reformed land zones and District Offices and Municipalities (Or. Bor. Tor) look after public land zones.
All land under the control of these government departments have no effect as to the rights of people who owned land before the government appointed the land as a forest, public or reformed zone. The law has retrospective effect on the individual's rights to land under the law before it became a forest zone.
That individual person still maintains its right to the land.