These women are from the tribe called: Long Neck Karen Ladies / Padaung Hilltribe...
“The Padaung are a sub-group of Karen (Bwe Group) living in Kayah state of eastern Burma on the Thailand border. They number less than 40,000 people in total. The Padaung call themselves "Lae Kur" or "Kayan". They have their own language which belongs to the Kenmic group in the Tibeto-Burman language family.
The Karen themseves are not one homogeneous group but rather a loose confederation of heterogeneous and closely related tribes. Among the smallest of the Karen tribes in Thailand are the Karen Padaung.”
The Padaung women famously wear brass rings around their necks. This distorts the growth of their collarbones and make them look as if they have long necks - which they don't. This row of brass rings do not actually stretch their necks but in fact squash the vertebrae and collar bones. A woman generally has about twenty or more rings around her neck. This neck ring adornment is started when the girls are 5 or 6 years old.
The rings on the arms and the legs are not quite as prominent as those on the neck simply because the neck rings are so pronounced. However, these rings are just as important. The rings on the arms are worn on the forearm from the wrist to the elbow. Those on the legs are worn from the ankles to the knees, and cloth coverings are kept over most of these rings, from the shins down to the ankles.”