The na of pāna is changed into ṇa , when occurs as the second member of a compound, the first member of which contains a letter causing change; and the whole compound denotes a country or people.,
The word पान is formed by the affix ल्युट् 3.3.113. Thus क्षीरपाणा उशीनराः = क्षीरपाणं येषां 'the milk-drinking Usinaras'. सुरापाणाः प्राच्याः 'the wine-drinking Prachyas'. सौवीरपाणा बाह्लीकाः \the sauvira-drinking Bahlikas\. कषायपाणा गान्धाराः &c.
Why do we say \when denoting a country\? Observe दक्षिपानं the drink of the Dakshis.
The words उशीनर and the rest are applied to persons also through the medium of being country-names.,