Colonel Biddulph ( Tribes of the Hindoo Koosh ) was amongst the first westerners to study Khowar and claimed that further research would prove Khowar to be equally derived from Zend ( Avestan , Old Persian ) and Sanskrit . John Biddulph ( Tribes of the Hindoo Koosh ) was amongst the first westerners to study Khowar and claimed that further research would prove Khowar to be equally derived from Zend ( Avestan , Old Persian ) and Sanskrit .