This is a reverse glass painting from western India, made by a Chinese artist. According to a description of the painting published on page 126 of the book ‘Reverse Glass Painting in India’ by Professor Anna L. Dallapiccola:
“In a hilly region, the sage Vasishtha sits on a tall throne in the shade of a tree, probably the kalpavriksha. In his right hand he holds a flower, which he will throw at Kamadhenu and her calf during his puja. Before him is a water pot, in which is yet another flower. The rishi wears a tall cap - possibly the Chinese artist did not understand the hair gathered in a tall jata makuta - and a flowing beard covers his chest. Instead of depicting Vasishtha seated on a deer skin, the artist chose to depict the deer skin on his lap. Opposite him is Kamadhenu, with a woman's face, long plaits, variegated wings, the tail of a peacock and two cows’ tails. Around her neck she wears the same ornaments in blue-black and red as worn by the sage, and a fetching hat is shown on her head. Her diminutive calf sucks at her teat.
This is a Chinese artist's version of a theme very popular in south Indian albums and 'Thanjavur' painting.”