Varuna is an Indo-Aryan deity. Some historians say that he is an Indo-Iranian deity (common to both the Iranian and Indo-Aryan speakers, dating back to the time when they were one people, and lived on the Central Asian steppes). Varuna was of great importance to the Indo-Aryan nomads. He was chief among the Asuras, a class of powerful gods who created the universe. Other Asuras included Mitra (who is closely associated with Varuna as Mitra-Varuna), Aryaman, Indra, Agni, and Soma.
He ruled over the cosmic ocean (called Rasa), and maintained the natural order (called Rta). Varuna could keep an eye on the entire cosmos and punish wrong-doers. ‘Ahura’ is the Iranian counterpart to the Indo-Aryan ‘Asura’. Some historians draw a comparison between the Vedic Varuna and the Avestan Ahura. It was around the time of the composition of the Vedas that he lost his primacy (to Indra). This took place after the Iranian and Indo-Aryan speakers had diverged, the former heading to the Iranian Plateau, and the latter to the Indus Valley.
I haven’t read of Varuna riding aquatic creatures in literature drawing upon the Vedas. Maybe, the representation of Varuna astride the Makara (mugger crocodile) was a later development, after the Indo-Aryans settled down in the Indus Valley and mingled with the non-Aryan inhabitants (who included Dravidian speakers). Asko Parpola hints at this in his observations about Makara iconography. It was also in the Vedas that one can see the ascent of Indra (who having defeated Vrtra, forced the older divinities, the Asuras, to retire to the underworld).
With Indra at the helm, the old gods were replaced by the new, namely, the Devas (Daevas in Iranian languages). To begin with, there was not much of a difference between the two sets of deities. With the passage of time, Asuras came to be associated with evil, and Devas with good, in South Asia. This transition was turned on its head in Zoroastrian Persia, where the benevolent Ahuras (with Ahura Mazda at the apex) fought off the malevolent Daevas.
Today, Varuna, and his successor, Indra, both lie on the margins of the Indian pantheon. Varuna leads an aquatic existence. His mount, the Makara, fared much better. It figures prominently in South, South East and East Asian art and architecture. Buddhists and Hindus have made use of the Makara in their stupas, carvings, temples and paintings. It has evolved from its simple reptilian form into a most astonishing fusion of creatures – elephant (trunk), crocodile (jaws), fish (body) and peacock (tail). The accompanying painting, however, stays true to the original idea.
Image Attribution: The image above is sourced from Wikimedia Commons and based on a late 17th century painting from Bundi, Rajasthan preserved by the Los Angeles County Museum of Art.
- The Disguises of the Demon: The Development of the Yaksha in Hinduism and Buddhism (by Gail Hinich Sutherland)
- Encyclopaedia Britannica
- Encyclopaedia Iranica