Arthashastra
इति पीडनानि आभ्यन्तरो मुख्य स्तम्भो बाह्यो अमित्र अटवी स्तम्भः ॥
Such is the group of molestations. Obstruction to movements caused by a chief is internal obstruction; and obstruction to movements caused by an enemy or a wild tribe is external obstruction.
english translation
iti pIDanAni Abhyantaro mukhya stambho bAhyo amitra aTavI stambhaH ॥
hk transliteration by Sanscript