The Danavas were the sons of Danu, who in turn was a daughter of Daksha. Danu is connected with the waters of heavens and she is probably associated with the formless, primordial waters that existed prior to the creation. The name is connected with the PIE root *danu,"river" or "any flowing liquid" and is associated with the river Danube. The Danavas revolted against the Devtas under the leadership of Bali and others, but were defeated. Danavas were classified as good and bad Danavas.David Frawley asserts that many ancient European peoples, particularly the Celts and Germans, regarded themselves as children of Danu, with Danu meaning the Mother Goddess, who was also, like Sarasvati in the Rig Veda, a river Goddess. The Celts called themselves Tuatha De Danaan, while the Germans had a similar name. The Greek ethnonym 'Danaan' is similarly related, see Mallory & Adams 2012:232 (Encyclopedia of Indo-European Culture). 
Ancient European river names like the Danube and various rivers called Don in Russia, Scotland, England and France reflect this. The Danube which flows to the Black Sea is their most important river and could reflect their eastern origins.
In Buddhism where they are known as the "bow-wielding" Dānaveghasa Asuras.
Some argue for an historical basis for the Vedic stories, and that the Danavas, and other defeated beings (Rakshasas, Gandharvas, Nagas, et cetera) were non-Aryan tribes, or that the Danavas in the Mahabharata, whose story is set in the region of the larger Indus river system, represent the Indus Valley Civilization, the builders of Mohenjo Daro and Harappa. But such historical readings of myth and legend are fraught with difficulties, and often are made selectively in support of pre-existing historical theories. There continues to be controversy over the idea of an Indo-European/Aryan invasion of India in some circles, and rival interpretations of Indian myth are one of the battlegrounds of that debate
3) Rahu - Son of Sinhika and Viprachitti
- Tribe of Dan
- Exotic tribes of ancient India
- Tuatha Dé Danann
- List of Asuras
- Rose, Carol (2000) Giants, Monsters, and Dragons: An Encyclopedia of Folklore, Legend, and Myth ABC-CLIO, Santa Barbara, CA, p. 94, ISBN 0-87436-988-6 ;
- Munro, W. D. (1911) Stories of Indian Gods & Heroes Harrap, London;
- "Vedic origins of Europeans: The Children of Danu"
- Senoupta, Prabodh Chandra (1951) "The Dānavas in the Mahābhārata" Journal of the Asiatic Society Series 3, 17: pp. 177-184, p. 182
- Elst, Koenraad (1999) Update on the Aryan Invasion Debate Aditya Prakashan, New Delhi, ISBN 81-86471-77-4 ;
- Frawley, David (1991) Gods, Sages and Kings Passage Press, Salt Lake City, Utah, ISBN 1-878423-08-8 ;
- Frawley, David (2001) The Rig Veda and the history of India: Rig Veda Bharata itihasa Aditya Prakashan, New Delhi, ISBN 81-7742-039-9 ;