A Kshatriya may take three wives. In two of them, he takes birth himself. His third wife being of the Shudra caste, is considered as very inferior. The son that he begets upon her is called an Ugra.
तिस्रः क्षत्रियसम्बन्धाद् द्वयोरात्मास्य जायते। हीनवर्णास्तृतीयायां शूद्रा उग्रा इति स्मृतिः॥