It is one of the "family books" (mandalas 2-7), the oldest core of the Rigveda, which were composed in early vedic period (1500-1000 BCE).
[1] The hymns are dedicated to Agni, Indra, the Visvadevas, the Maruts, Mitra-Varuna, the Asvins, Ushas (Dawn), Indra-Varuna, Varuna, Vayu (Wind), two each to Sarasvati, Rudra, the Waters, the Adityas, Vishnu, Vastospati, Brhaspati, one each to the Apris, to Vashista, Savitar, Bhaga, the Dadhikras, the Rbhus, Dyaus and Prthivi (Heaven and Earth), Parjanya (Rain) and Indra-Soma.
The rivers mentioned in the 7th Mandala are the Sarasvati, Asikni, Parusni and possibly the Yamuna (in 7.18.19 the name of a helper of Indra, maybe also the name of a woman or goddess).
The battle took place during the middle or main Vedic period,[3] near the Ravi river in Punjab.
It was a battle between the Puru kingdom, allied with other tribes of the northwestern India, guided by the royal sage Vishvamitra, and the Bharata king Sudas, who defeated the Purus.