They visit Namucuo (commonly known as Nam Co or Nam Tsho, a high salt lake.

Teng writes:

It was evident that all mountain ranges converged on the lake, and there was an island emerging from the centre of the lake. Together, they formed “The Dragon Celebrating Pearl Formation” that facilitated Tibet’s spirituality.

Incidentally, Teng (and other sources) refer to Nam Co as “highest lake on earth,” but there are other, higher lakes, including Orba Co, the site of the highest islands in the world.

Inhabited islands are eroding away, as the Ganges Delta shifts, possibly abetted by sea level rise.

The Independent (UK) reports the disappearance of Lohachara as the first sinking of an inhabited island caused by climate change, and suggests that 12 islands with a population 70,000 are in danger.

While the danger of rising seas appears real, islands disappear (and appear) in this deltaic region on the Bay of Bengal all the time, and it might be hard to pin this particular instance on the small sea level rise that has occurred so far.  Indeed, Lohachara might be a char – the Bangladeshi name for the notoriously shifting and often temporary river deposits that land pressure forces desperate people in the region to live on.

The Sentinelese, thought to number between 50 and 200, have rebuffed all contact with the modern world, firing a shower of arrows at anyone who comes within range.  They are believed to be the last pre-Neolithic tribe in the world to remain isolated.

DNA suggests they have been isolated for a very long time indeed:

DNA analysis of another tribe, the Jarawa, whose members made first contact with the outside world in 1997, suggest that the tribesmen migrated from Africa around 60,000 years ago.