Which of the following castes is not included in the prehistoric castes of Himalayan region ?

Gandharv
Yaksha
Kinnar
Shak

The correct answer is (d), Shak.

The prehistoric castes of the Himalayan region are:

  • Gandharv: A caste of musicians and dancers.
  • Yaksha: A caste of nature spirits.
  • Kinnar: A caste of half-human, half-animal creatures.

Shak is not a prehistoric caste of the Himalayan region. It is a caste of people who are believed to be descended from the Shakas, an ancient Indo-Scythian people.