The country of Surparaka (Sanskrit: शूर्पारक, Śūrpāraka) was founded by Bhargava Rama (also known as Parashurama) near the Western sea, close to the mouth of river Narmada. This kingdom is mentioned in the epic Mahabharata. Parashurama gave this kingdom to the Brahmin rulers of Kashyapa clan. Surparaka is identified with medieval Sopara and modern day Nala Sopara.
This gave rise to the myth of Parashurama, reclaiming the land from the sea. The people of Surparaka brought this myth to Kerala where this myth still exists.
References in Mahabharata
Ocean created for Jamadagni’s son (Bhargava Rama), a region called Surparaka (12:49). Having made the earth destitute of Kshatriyas for thrice seven times, the puissant Bhargava, at the completion of a horse-sacrifice, gave away the earth as sacrificial present unto Kasyapa. Kasyapa having accepted the earth in gift, and made a present of it unto the Brahmanas, entered the great forest.
The pilgrimage in Surparaka
One should proceed to Surparaka, where Jamadagni’s son had formerly dwelt. Bathing in that tirtha of Rama, one acquireth the merit of giving away gold in abundance. (3:85). In the tirtha called Surparaka are two sacrificial platforms of the illustrious Jamadagni, called Pashana and Punaschandra (3:88). Yudhishthira plunged his body in all the holy spots, and then came again to Surparaka (3:118). Bathing in the Narmada as also in the tirtha known by the name of Surparaka, observing a fast for a full fortnight, one is sure to become in one’s next birth a prince of the royal line. (13:25).
Sahadeva's Expedition to south
Having brought king Nila of Avanti under his sway the victorious son of Madri, viz. Sahadeva, then went further towards the south. He then brought the king of Tripura under his sway. And next turning his forces against the Paurava kingdom, he vanquished and reduced to subjection the monarch thereof. And the prince, after this, with great efforts brought Akriti, the king of Saurashtra and preceptor of the Kausikas under his sway. The virtuous prince, while staying in the kingdom of Saurashtra sent an ambassador unto king Rukmin the son of Bhishmaka within the territories of Bhojakata. And the monarch cheerfully accepted the sway of the son of Pandu. And the master of battle then, having exacted jewels and wealth from king Rukmin, marched further to the south. And, endued with great energy and great strength, the hero then, reduced to subjection, Surparaka and Talakata, and the Dandakas also (2:30).
References in Mahavamsa
The Mahawamsa, the Sri Lankan Pali chronicle, mentions that the legendary founder of the Sinhalese, prince Vijaya, left his homeland of Lala and landed first in Suppäraka (the Pali form of the Sanskrit Surparaka) identified with modern Sopara, in Palgar district north of Mumbai. Mahawamsa, Chapter 6