Explanation

Gandhara Civilization flourished in Pakistan during the rule of Buddhist Kings.

Taxila was considered as Pearl of Gandhara Civilization. 

language of the Gandhara civilization was:  Prakrit

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Gandhara's language was a Prakrit or "Middle Indo-Aryan" dialect, usually called Gāndhārī.

Hindko from Peshawar, which was the capital of Gandhara, came from Shuraseni Prakrit a language spoken in Gandhara.