Source: here.
The mahA-chInAchArya, shubhakara siMha, a nAstIka of the second varNa, was a remarkable, even if forgotten, figure in history largely forgotten in his homeland India. He was a descendent of the ikShvAku chieftain amR^itodana whose clan held a small kingdom in what is the border between modern Madhya Pradesh and Orissa. They were overthrown by the rAShTrakUTa army and as a consequence fled to oDDiyAna pITha in central Asia. Here they established themselves as rulers of oDDiyAna. It was here that shubhakara siMha was born. His father believed he saw the signs of divine favor in him. Just then the brutal onslaught of the terror called Islam was spreading into central Asia under the directives of the Umayyad Kalifs. shubhakara siMha was put in command of his army at the tender age of 10 years and led his troops to a great victory against the marauding Moslems. The chIna records mention how the kingdom of oDDiyAna repulsed the attack of the Moslems. At the age of 13 his father died and he was declared rAjan of oDDiyAna. He was a popular ruler, but this sparked an intercine conflict with his brothers in course of which he was wounded on his head by the blow of a chakra and an arrow. He however crushed his brothers and regained total control of the kingdom. After this intercine war he is said to have lost interest in the kingdom, and released his defeated brothers and handed the kingdom to the eldest of them. He decided to take sannyAsa prematurely. But his mother gave him an ancestral pearl, which the symbol of inheritence of the oDDiyAna throne, before he left the palace. He travelled south to saindhava, where he wandered on the shore studying the nAstIka tantras of the bauddhamata. After rigorous japa and yoga he became a great tantric. He found a ship of vaishyas setting forth on a trading expedition around the coast of India to the far East. They agreed to take him along on the journey, and on the ship he kept performing various japa-s to 7 crore devatA-s.
It was said that a white light emanated from his mouth as he was performing his secret yoga. Once when wind did not blow for 3 days he is said to have allowed the ship to go a long way with his mantra prayoga-s. Then the merchants were attacked by Moslem pirates. He performed another prayoga and the deva-s sent another band of pirates that destroyed the Arab pirates. The ship then found his way by sea to Orissa, where he saw a rAjan who had married his sister. He discussed various tantric issues with his brother-in-law, who then came to terms with his renunciation. He then proceeded to Nalanda and studied the highest of the bauddha tantras under the master of the dharaNis, dharmagupta. shubakara siMha was initiated into the path of the great yoga by which he could suddenly attain enlightenment. Having attained enlightenment he wandered on kukkuTa-parvata where he saw mahAkAshyapa in meditation. He cut his over grown hair and the lokeshvara placed his hand on his head providing him highest bliss. He spent the monsoons in gR^idhrakUTa where a lion lead him to a cave, where he saw a vision of the shAkyamuni, the founder of the nAstIka mata.
In his ancestral land in Malva the people were suffering from a major drought and called upon shubhakarasimha to help them. He performed a great sahasrabhuja lokeshvara prayoga by invoking him in the sUrya maNDala and apparently brought down rain to relieve the land. He then engaged in debates with AstIkas and other nAstIkas like the jainas and hInayAna bauddhas in different parts of jambudvIpa. He is said to have spread the bauddhamata with great fervor in his debating spree.