Markandeyapurana 49.36

49.36

kṛtrimañca tathā durgaṃ mitvā mitvātmano/ṅgulaiḥ /
mānārthāni pramāṇāni tāstu pūrvaṃ pracakrire //

Afterwards in course of time those people grew covetous besides; their minds being filled with selfishness they fenced the trees[6] round; and those trees perished by reason of that wrong conduct on their part. Strife sprang up in consequence; their faces felt cold and heat and hunger. Then for the sake of combination and resistance they made towns at first; and they resort to fortresses in inaccessible deserts and wastes, in mountains and caves; also they industriously constructed with their own fingers an artificial fort on trees, on mountains and in water, and they first made measures intended for measurement.