Ṛthu is one of those rājarṣis (rajarshi; king with the attributes of a sage-seer), who, in ancient times, achieved ṛṣitva (rishitwa; the status of a seer-sage) or brahmarṣitva (brahmarshitwa; the status of the brahmana sage) by practicing tapasyā (tapasya; penance or asceticism).