There are Seven Seers of Hinduism called as Saptha (seven) Rishis.
According to Puranas,these change for every Manvantara,a Time scale of Hinduism going back to lakhs of years.
For more read my article on Manvatara.
The Saptha Rishis for our Manvantara are,
It is interesting to note that references to these Rishis are associated with certain regions of the world,though all of them are from Bharatavarsha.
Bhrighu from Himachal Pradesh,Kutsa from near Uttar Pradesh,Vasishta from Indus valley,Atri,Kasyapa and Gautama and Angirasa are from the south of Vindhyas.
It is also curious that the Bhargavas,those from Bhrighu Lineage, to which Parashurama,an Avatar of Vishnu,are sometimes treated as those from the south,with Parashurama establishing Goa and Kerala regions of today.
Kasyapa is the earliest and his name means Turtle.
The Turtle concept is present in almost all lehends related to Creation of Earth.
Kasyapa must have lived in the south ,though he is reported to have come to south twice .
Once when the earth was tilted during Shiva,s Marriage with Uma and again during Ramayna whe he came down to Lanka to impart The Adityahridhaya Stotra on Surya,the Sun God,to Lord Rama,when he was depressed during his battle with Ravana in Lanka.
Agastya’s movement has been validated by the Star Canopus.
Please read my article on this.
Sage Gauthama was from the Godavari basin/valley,the River Godavari is named after him.
Bhrighu and Angirasa are classified as pre Vedic Rishis.
Though they are referred thus and are mentioned in The Zend Avestha of Zoraosterianism,Angirasa ,going by Sumerian and Tamil related material was from the Dravida desa and he seems to have founded the Akkadian empire or worshiped by them.