In order to make a scientific study on the history of any land, a broad and thorough knowledge of its geography is essential. It will be certainly not easy on the part of a historian to look into the course of events unless he possesses accurate information about the precise location of various places that figure significantly in the narrative. On the other hand, no historian of a state can overlook the immense influence of its physical features that play a vital role in shaping the character of its people and their socioeconomic and political condition of a state.
The Geographical importance of places in relation to historical significance brings forward the concept of ‘historical geography’. Historical geography essentially aims at the reconstruction of geography of a region of a period which has already passed. By putting together pieces of scattered evidence, all aspects of geography of that period can be reconstructed. In this context, the historical geography of ancient Odisha deserves special attention. The region now known as Odisha, was known in ancient times under various names, the most prominent of which were Kalinga, Utkala, Odra, Tosali , Kangoda and Kosala. To have an idea about the ancient geography of Odisha it is necessary to have an idea about the antiquity and extent of main ancient geographical units. Each of them during its historical existence found mention in different sources which provide interesting accounts about it. The ancient geographical units can be discussed as follows:
All these geographical units have played their roles in the enrichment of political and cultural history of the Odisha. As we observe that Kalinga, Utkala, Odra, Tosali , Kongoda and Kosala were territories having distinct boundaries of their own and the boundary changed from time to time in ancient and early medieval period. Sometimes, it is noticed that some of these names were used as interchangeable terms, e.g. Odra was known as Tosali during the Bhaumakara At the advent of fifteenth century A.D. poet Sarala Dasa made Udisa or Odisha synonym with Odrarastra which became Odisha rajya during the great Gajapatis. Right from the days of Kapilendradeva (1435-1467 A.D.), this empire land of the Odia speaking people has been known as Odisha.