There is various places referred to as Dakshinapatha. There is no argument on the definition that road leading to south India is Dakshinapatha later on whole of south called Dakshinapatha, it is based on who says it and in what context.
Ancient Buddhist and Brahmanical texts use the term Dakshinapatha as a name for both the southern high road of the Indian subcontinent, and for the region lying south of Majjhimdesa or middle India. It is derived from the two Sanskrit roots dakshina for south, and patha for road.
The first reference to Dakshinapatha occurs in the Rig-Veda where it refers to the region of exile. In the opinion of several scholars, this means the South beyond the limits of the Saptasindhu-- the region of the culture of the Rig Veda.
Dakshinapatha is referred to by Panini. Baudhyana mentions Dakshinapatha or Dakshinatya in association with Saurashtra.
Jataka and Vinaya Pitaka use the name Dakshinapatha coupled with Avanti as in Avantidakshinapatha where it seems to refer to the janapada of Avanti, and implies its location in Dakshinapatha. The Sutta Nipata commentary seems to explain Dakshinapatha as the road leading to the Dakshinajanapada, the latter name referring to a Janapada located to south of the Ganges. In the same Sutta Nipata, the name Dakshinapatha also refers to a remote settlement located on the banks of the upper Godavari.A Kosala Brahmin named Bavari had left Savathi (capital of Kosala) to set up his hermitage at the junction of river Mula and Godavari, midway between the kingdoms of Assaka and Mulaka (in modern Maharashtra), which place has been noted as lying in Dakshinapatha.
In the Mahabharata, Dakshinapatha is placed beyond Avanti and the Vindhyas, and to south of the kingdom of Vidarbha and southern Kosala, the latter being located on the banks of Wardha and Mahanadi. In Dighvijayaparva of Mahabharata, Dakshinpatha is distinguished from the Pandya country to the south.
When Rama set out from Ayodhya into his voluntary exile, he took a route which extended from Ayodhya into Dakshinapatha or the southern direction.
Kautilya's of Dakshinpatha mentions southern part of the mauryan empire as dakshinapatha (Karnataka)
According to Puranic accounts, the janapadas of Asmaka, Mulaka, Vaidarbha, Kalinga, Andhra, Pundra, Pulinda, Dandaka, Kuntala, Kerala, Pandya, Chola and others lay in the Dakshinapatha.
In the Petavatthu commentary, the Damila i.e Dravida country is included in the Dakhinápatha.
On their way to Rajagriha, the pupils of the ascetic Bavari from Dakshinapatha (Godavari) had followed a route which led them through Pratishthana (modern Paithan), Mahesvar, Ujjaini, Gonaddha (Gond country), Bhilsa (Bhil country), Kosam, Saketa (Faizabad), Savathi, Setavya, Kapilavastu, Kusinara, Pava, Bhoganagar, Vaisali and then to Rajagriha (in Magadha).
Thus, initially, Dakshinapatha, as high road, ran between Rajgriha and Pratishthana. Later, it also extended further into the south running parallel to west-coast and following probably through Bijapur, Bangalore and Madura to either Rameshwaram or to Kanyakumari, the southern tip of India.
Dakshinaptha as a region extended from the land of the Kosalas to the kingdom of Kanchi. In later times however, it had embraced the whole of Trans-Vindhya India from Setu (Rama's Bridge) to the Narmada.
Ancient Dakshinapatha later gave its name to modern Deccan or Dekkan. From the above, it is clear that, in the earlier literature at any rate, the word Dakshinapatha did not mean it initially comprised the whole country in the modern word Dekkhan or Deccan.Dakshinapatha should be understood in relation to Uttarapatha the northern high road and later the northern division of Puranic Jambudvipa.