Arthashastra
जन पदं च एकस्थं शैल वन नदी दुर्गेष्व् अटवी व्यवहितेषु वा पुत्र भ्रातृ परिगृहीतं स्थापयेत् ॥
the enemy's people should also be kept under the protection of sons and brothers (of the conqueror) in some forts on a mountain, or in a forest, or in the midst of a river separated from the enemy's country by wild tracts of lands.
english translation
jana padaM ca ekasthaM zaila vana nadI durgeSv aTavI vyavahiteSu vA putra bhrAtR parigRhItaM sthApayet ॥
hk transliteration by Sanscript