The sum of my research into the nature of Gandhara (Peshawar Valley and environs) reveals that “original” Gandhara — which existed from 550 BC, upto 500 years ago — had more or less this kind of demographic breakup:
1) Hindkis (majority — Indo-Aryan): Also known as Gandharis. They were kasabgars, i.e artisans, craftsmen and menials. Later Gujjars were added to this category. They take their name from Hindko, the Gandhari Prakrit dialect. They are now still the same, yet wholly Pashtunised.
2) Dards (of the Tirahi type — Indo-Aryan): An early form of Dard, these “wild Kohistani” Indo-Aryan tribes were both Hindu and Muslim, constituting a powerful and widespread landowning class. The original Hindu variants were known as “Parbati” (mountaineers) and were declining demographically; nowadays they have become the prominent Mian families of Peshawar Valley (it will be noticed that the term Mian is Indic). An interesting fact is that the bringing of Karlani Pashtuns here by Sultan Mahmud from the Greater Paktia area caused the Tirahis to undergo not just Islamisation, but progressive Pashtunisation as well, and in this manner they added to the Karlani Pashtun category.
3) Karlani Pashtuns (Eastern Iranian): Mentioned above….they were mostly Dilazaks who survived on soldiery, raiding and robbery.
4) Shalmanis (Tajiks — Iranian): Present here since the time of Persian rule as a landowning (Dehqan) class which collected the revenue and enforced the administrative duties of the Persian Empire, they formed an elite minority. After the conquest of imperial Persia by the Arabs in 651, they were replaced by a 350 year period of Rajput-Gujjar dynasties (Kabul Shahis and Hindu Shahis) — till the time of the Ghoris in 1180, when a branch of the now Muslim Shalmanis from Kunar — called the Suwadis (Swatis) — was placed in power over the conquered Gandhara from Swat, by Shahabuddin Ghori. Later, the Shalmani-Swati dispensation was overthrown by the Sarabani Afghan incursions and revolt in Peshawar Valley, and they were absorbed and Pashtunised as junior partners in the setup of the former.
The name Gandhara/Kandahar began disappearing from public usage during the Swati time — and it was from 1275 that the modern Afghan city of the same name suddenly “appears” in the record.