In Hinduism, a Brahmarshi (Sanskrit brahmarṣi, a tatpurusha compound of brahma and ṛṣi) is a member of the highest class of Rishis ("seers" or "sages"), especially those credited with the composition of the hymns collected in the Rigveda. A Brahmarshi is a sage who has understood the meaning of Brahman or has attained the highest divine knowledge Brahmajnana.
Bhrigu, Angiras, Atri, Vishwamitra, Kashyapa, Vasishta, and Shandilya are the seven brahmarishis. But there is another list of Saptarishi also who are also Gotra-pravartakas, i.e.,founders of Brahamanical clans, and this second list appeared somewhat later, but belongs to ancient period.
All the hymns of third mandala of the Rig Veda is ascribed to Vishwamitra who is mentioned as son of Gadhi, including the Gayatri mantra. According to Puranic stories, Vishwamitra was the only brahmarishi who rose to the position out of pure tapas. Originally belonging to the kshatriya, he rose by pure merit to a Brahmarishi. Vishwamitra is also referred to as Kaushika, because he attained Brahmajnana on the banks of the river Koshi.
The Period of the Vedas
Brahmarshi-desha, 'the county of the holy sages,' includes the territories of the Kurus, Matsyas, Panchalas and Surasenas (i.e. the eastern half of the State of Patiala and of the Delhi division of the Punjab, the Alwar State and adjacent territory in Rajputana, the region which lies between the Ganges and the Jumna, and the Muttra District in the United Provinces).
- Rapson, E. J. (1914). Ancient India, from the earliest times to the first century, A.D.. (pp.50-51)