Kautilya's Arthashastra 2.1.3

2.1.3

nalīśailavanabhṛṣṭidarīsetubandhaśamī.śālmalīkṣīravṛkṣān anteṣu sīmnāṃ sthāpayet //

Villages consisting each of not less than a hundred families and of not more than five-hundred families of agricultural people of súdra caste, with boundaries extending as far as a krósa (2250 yds.) or two, and capable of protecting each other shall be formed. Boundaries shall be denoted by a river, a mountain, forests, bulbous plants (grishti), caves, artificial buildings (sétubandha), or by trees such as sálmali (silk cotton tree), samí (Acacia Suma), and kshíravriksha (milky trees).