Genetic analysis of the Mlabri group by Hiroki Oota and colleagues led them to observe that the mtDNA has little diversity, suggesting to them that the Mlabris were founded 500-800 years ago from very few individuals. This hypothesis was contested in the journal PLoS Biology in 2005 in an exchange of articles between Hiroki Oota and colleagues, and Tony Waters.

The Mlabri language is usually classified as a Khmuic language, a subgroup of the Mon-Khmer languages. Linguist Jørgen Rischel has studied the language and described its peculiarities in several works. He divides the language into three varieties: one spoken by a small group in Laos and previously called Yumbri, and two others spoken by larger groups in Thailand. They differ in intonation and in lexicon.

German anthropologist Hugo Bernatzik published an ethnography of the "Yellow Leaf People" in 1938 which reflected his brief observations of the tribe in the mid-20th century.

The Mlabri are an enigmatic group of about 300 people who, until a few decades ago, used to live a nomadic life as hunters and gatherers in the dense forests and high mountains of Northern Thailand. They would build temporary structures of bamboo sticks thatched with fresh, green banana leaves and occupy these for a few days, until the leaves turned yellow.

Since the proof of their existence consisted mostly of these abandoned huts, they were given the traditional Thai name of “Phi Tong Luang”, meaning “Spirits of the Yellow Leaves”. However, since they are peaceful people, they wish to be referred to as “People of the forest”  

 
  There is some controversy about the Mlabri’s origin, but at present they are recognized as (new) Thai citizens. They have had to struggle long time for this, and many problems started when their natural habitat was diminishing due to deforestation, making their traditional way of life less and less possible. Because they couldn’t have their own land, they had to work for other tribes and often faced slave like servitude, forced tour shows and other degrading alternatives.
Some 20 years ago, they started receiving help from a missionary and his family. Great steps were achieved in the areas of education and health, but the need for a steady income remained.
  
 
 
In 1996, an intrepid Suisse motorbike tour guide, Peter Schmidt, who had formerly worked as a textile engineer, discovered the village and was struck by the women's skills in making string bags from the fiber of jungle vines. Occasionally these bags would make a sale as souvenirs, but never enough to become a reliable source of income. Peter offered his knowledge of weaving hammocks in order to help, opened the first shop near Chiang Mai and that was the beginning of one of the most successful development projects in the area.  
 
The Mlabri adopted this new handicraft that seemed to go quite well with their quiet life style and started off with the production of the original Mlabri hammock, a.k.a. the Jungle Hammock. Meanwhile, they have also mastered the quite tricky process of dying the cotton yarn as well as the most intricate weaving techniques such as V-weaves and Silk hammocks. Men have joined the workforce and production has expanded to include eight different styles of hammocks that are being exported to more than 15 countries world wide.

Unlike in sweatshops, the goal was not to simply mass produce at lowest cost, regardless of any human needs of the laborers. The idea rather aimed at offering financial independence for the Mlabri while enabling them to continue as much as possible with their own lifestyle. That also means that every hammock is produced in a healthy and family oriented environment (the home village) and the workers are paid honest wages. Money is set aside for healthcare and education and there is even a steadily growing social fund. None of this would have been possible without the Mlabri’s own enthusiasm.
 
 

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Links;

Fernthai.Org Wapedia  Hammock House Lanta (Mlabri Hammocks)