Analysis of information sources in references of the Wikipedia article "Gandhari language" in English language version.
Palula belongs to a group of Indo-Aryan (IA) languages spoken in the Hindukush region that are often referred to as "Dardic" languages... It has been and is still disputed to what extent this primarily geographically defined grouping has any real classificatory validity... On the one hand, Strand suggests that the term should be discarded altogether, holding that there is no justification whatsoever for any such grouping (in addition to the term itself having a problematic history of use), and prefers to make a finer classification of these languages into smaller genealogical groups directly under the IA heading, a classification we shall return to shortly... Zoller identifies the Dardic languages as the modern successors of the Middle Indo-Aryan (MIA) language Gandhari (also Gandhari Prakrit), but along with Bashir, Zoller concludes that the family tree model alone will not explain all the historical developments.
...This leads us to the conclusion that the ancient dialects of the Peshawar District, the country between Tirah and Swât, must have belonged to the Tirahi-Kohistani type, and that the westernmost Dardic language, Pashai, which probably had its ancient centre in Laghmân, has enjoyed a comparatively independent position since early times". …Today the Kohistâni languages descendent from the ancient dialects that developed in these valleys have all been displaced from their original homelands, as described below.
In the Peshawar district, there does not remain any Indian dialect continuing this old Gandhari. The last to disappear was Tirahi, still spoken some years ago in Afghanistan, in the vicinity of Jalalabad, by descendants of migrants expelled from Tirah by the Afridis in the 19th century. Nowadays, it must be entirely extinct and in the NWFP are only to be found modern Iranian languages brought in by later immigrants (Baluch, Pashto) or Indian languages brought in by the paramount political power (Urdu, Panjabi) or by Hindu traders (Hindko).
... It might be going too far to say that Torwali is the direct lineal descendant of the Niya Prakrit, but there is no doubt that out of all the modern languages it shows the closest resemblance to it. A glance at the map in the Linguistic Survey of India shows that the area at present covered by "Kohistani" is the nearest to that area round Peshawar, where, as stated above, there is most reason to believe was the original home of the Niya Prakrit. That conclusion, which was reached for other reasons, is thus confirmed by the distribution of the modern dialects.
... It might be going too far to say that Torwali is the direct lineal descendant of the Niya Prakrit, but there is no doubt that out of all the modern languages it shows the closest resemblance to it. A glance at the map in the Linguistic Survey of India shows that the area at present covered by "Kohistani" is the nearest to that area round Peshawar, where, as stated above, there is most reason to believe was the original home of the Niya Prakrit. That conclusion, which was reached for other reasons, is thus confirmed by the distribution of the modern dialects.