Pashto (پښتو; also known as Afghan, Pushto, Pashto, Pashtoe, Pashtu, and Pukhto) is the language spoken by the ethnic Afghan otherwise known as the Pashtun people who inhabit Afghanistan and the Western provinces of Pakistan.
The desire to unify theses disparate regional and communal cultures of India were reflected in the desire to codify the disparate interpretations of rags and tals into a single cohesive whole.
It is not clear why pashtu failed to be amalgamated under the heading of rupak tal.
Perhaps it was because the usage of pashtu was geographically too far from the present boundaries of India; the name "pashtu" implies the area on the Pakistan / Afghanistan border.