Kautilya's Arthashastra 3.7.32

3.7.32

vaidehikāyām ambaṣṭhād vaiṇaḥ, viparyaye kuśīlavaḥ //

The son begotten by an Ugra on a Nisháda woman is called kukkuta and the same is called Pulkasa, if begotten in the inverse order. The son begotten by an Ambhashtha on a Vaidehaka woman is named Vaina; the same in the reverse order is called Kusílava. An Ugra begets on a Kshatta woman as vapáka. These and other sons are of mixed castes (Antarálas).