The Collaborative International Dictionary of English v.0.48:

Poonah painting \Poo"nah paint`ing\ [From Poona, in Bombay
   Province, India.]
   A style of painting, popular in England in the 19th century,
   in which a thick opaque color is applied without background
   and with scarcely any shading, to thin paper, producing
   flowers, birds, etc., in imitation of Oriental work.

   Note: Hence:

   Poonah brush,

   paper,

   painter, etc.
      [Webster 1913 Suppl.]