Among the different political units of this ancient land, Kalinga occupied a prominent place. The fertile coastal plains stretching from the mouth of the river Ganges up to Godavari, with mountains and forests, gave a natural boundary to Kalinga. The name Kalinga occurs in the Puranas in association with Anga, Vanga, Pundra and Sumha. In the Mahabharata there is an indication about the location and the extent of Kalinga. In the Vana Parva the sage Lomasa pointed out, “This is the country of the Kalingas where flows the river Vaitarani.” This evidence clearly indicates that the land now known as Odisha was included in the Kalinga country, but its extent in the Mahabharata age cannot be determined. The epic account also finds substantiation in the works of early Greek writers. In the description of Megasthenes, the river Ganges forms the eastern boundary of Kalinga. Pliny divides Kalinga into three parts Viz- Gangarides Calingae, Maceo Calingae and Calingae. Its southern boundary, as per Pliny’s description, is limited on the bank of the river Godavari basing upon the puranas like Matsya, Kurma and Skanda, the western frontier of Kalinga is supposed to have stretched upon the Amrakantaka hills on the river bank of Narmada. Thus, as per the Puranic tradition, Kalinga is said to have extended up to the Gangetic valley in the north, the Godavari in the south, the sea in the east and the Amrakantaka hills in the west.
In the list of the sixteen Mahajanapadas of the sixth century B. C., described in the Pali literature Kalinga does not appear as one, but this omission does not mean that, Kalinga did not exist as a Mahajanapada or a great state. In the fourth century B. C., Kalinga was under the suzerainty of the Nandas. In the third century B. C. during the period between the Nandas and Mauryas, it slipped away from the fold of Magadhan imperialism. With Ashok’s Kalinga war of 261 B. C., it came again under the authority of Magadha. His Special Edicts (also known as Kalinga Edicts) at Dhauli near Bhubaneswar, are addressed to the Mahamatras and the Kumaramatya (prince viceroy) of Toshali, while his same edicts at Jaugada in the Ganjam district are addressed to only the Mahamatras of Samapa. From these two inscriptions of Asoka now to be found in Odisha, it becomes apparent that for the sake of administration he had divided the Kalinga country into two broad divisions, northern and southern. In the northern division the capital Tosali was situated, while Samapa formed the second capital in the southern division.
The evidence furnished by Asoka’s Inscription thus clearly proves that Kalinga in his time included the entire region now known as Odisha, though its northern and southern boundaries cannot exactly be determined. It seems, however, that its southern boundary extended up to the river Godavari. The northern limits of Kalinga of Asoka’s time cannot be determined.
During the second century B.C. the present state of Odisha was certainly known as Kalinga as is evident by the fact that in the Hatigumpha Inscription at Udayagiri near Bhubaneswar, Kharavela is described as Kalingadhipati. During his reign, Kalinga expanded into an empire, the extent of which is variously determined by scholars. We do not know when his empire became dismembered, but even after the fall of his empire the land of Odisha continued to be called Kalinga. By the fourth century A.D. when Kalidasa wrote his Raghuvamsam, Kalinga seems to have been divided into two regions, of which the northern region was known as Utkala. In the fourth stanza of his work it is stated that the people of Utkala showed Raghu the path to Kalinga. In the Allahabad Inscription of Samudragupta, it is stated that during his southern campaigns Samudragupta conquered Kottura, Pishtapura, Erandapalli and Devarashtra, which have been identified with Kothoor in the Ganjam district, Pithapuram in the Godavari district, Erandapalli and Yellamachilli in the Visakhapatanam district respectively. In one of the earliest copper plate records of Odisha, known as Sumandala Copper Plates of Prithvivigraha, Kalinga as a rashtra (kingdom) has found mention, but in the subsequent medieval epigraphic records the name Kalinga does not appear. This does not, however, mean that Kalinga as a geographical name became extinct. It continued to be applied to the territory between Ganjam and the river Godavari in the subsequent ages down to the Ganga and Suryavamsi periods.
Dantapura, one of the early capitals of Kalinga, has not been identified. Various suggestions made by scholars about its location and its identity still remains to be confirmed by archaeological evidences. Kalinganagara which was capital of Kharavela, has tentatively been identified with Sisupalagarh near Bhubaneswar. The Early Eastern Gangas established their capital at a place which was also known as Kalinganagara and it has been identified with Mukhalingam in the Srikakulam district by Mr. R. Subbarao, though there are also other suggestions for its identification. Kalinganagara ceased to be the capital of the Gangas when Chodaganga conquered Odisha about A.D. 1110 and he chose Kataka (Cuttack), more centrally situated in his extended kingdom, as his new capital.