Mahanaga was an early monarch of Sri Lanka of the Kingdom of Ruhuna in the southern region of the island.
The king Mutasiva had nine sons, including Devanampiya Tissa, Uttiya, Mahasiva, Mahanaga and Asela.
According to the customs of Anuradhapura kings, Uttiya, Mahasiva and Mahanaga should have come to the throne next.
One day when Mahanaga was working with his men in a field, the queen sent them a basket of poisoned mangoes.
Prince Mahanaga thought, it's not good to be in the city, and left Anuradhapura with his family and men and migrated to Ruhuna.