Herodotus has a story (2.2) about the Egyptian king Psammetichus wanting to know which was the oldest language, so he had two babies raised by a shepherd who was told not to utter any words in their presence but to take note of the first word they said. One day the children came to him and said "bekos" (accent on the "o"). Psammetichus investigated and discovered that bekos was the Phrygian word for "bread," and so he concluded that Phrygian was the oldest human language.
If it's in Herodotus, it has to be true.
The question is how a relative of Phrygian would wind up in Pakistan. The Persians used to transplant populations--conceivably they could have transplanted some Phrygians to that area. But that only works if the language is a descendant of Phrygian--it may be more like a cousin.
Good logical deduction. They could be also from Alexander’s armies?