Tarascus is the king of Nemedia; he gained the throne by killing his older brother, the former king of Nemedia, by the help of the ancient wizard Xaltotun. They raised Xaltotun from the dead by using the Heart of Ahriman. Once crowned, Tarascus immediately declared the truce between Nemedia and Aquilonia void, and started gathering the army to invade the kingdom to the south. He wanted to dethrone Conan, the current king of Aquilonia, in order to crown Valerius king of Aquilonia.
Through the help of Xaltotun, they managed to get Valerius crowned as king, while the people of Aquilonia thought Conan to be dead, slain in the first battle between Nemedia and Aquilonia since the truce was broken. However, was not killed, but was being held captive by Xaltotun in Belverus, the capital of Nemedia. Conan managed to escape, and after getting his hands on the Heart of Ahriman he rallied an army from Poitain, Gunderland and the Bossonian marches. The Heart of Ahriman was used by the priest of Asura, Hadrathus, to slay Xaltotun, and Conan regained his throne.
After the battle where Xaltotun was slain, Tarascus, on the loosing side, was at the mercy of Conan. Conan however wanted only Zenobia as his ransom.