According to legends, Brahma celebrated his court with Devas and Sages, at that time, his consort, Saraswati Devi entered court. She looked extremely beautiful at that time. Her elegant and charming appearance distracted Brahma. He finished his court immediately and left the place with his wife to a divine place. He asked her to appear in hundreds of ways to show it. As a result, they were blessed with a hundred devilish children. They were cannibals, chaotic and more destructive. Brahma ordered them to go to Vindhya Mountain and live there. After reaching the hills, these demons began to disturb the innocent. Disturbed by these ruinous activities, the goddess of the earth (Bhudevi) appealed to Brahma to save her. Brahma created a son named Ugra and ordered him to kill demons. As ordered, Ugra killed the demons and reported the same to his father. Hearing this, Brahma became furious and turned Ugra into ashes.
Brahma became aware of his guilty act. He moved to Dakshina Kailasa (Sri Kalahasti) with his wife Saraswati Devi and performed severe penance for Lord Siva. Siva appeared before Brahma with his wife Paravati and urged them to continue penance on the same hill for a year, starting the day of the star Makha in the month of Margasira. Siva also granted Brahma’s wish for a worthy son at the end of Tapas.
Lord Brahma and Saraswati Devi were blessed with a son named Ribhu. Then he became a great sage.