The history of Greek settlement in the north-western part of India before Alexander’s invasion is only known from coins. Even the history of Satavahanas, about whom the different version of the Puranas give different genealogical and chronological list of kings are known from coins alone.
While writing Oriya history, historians like Sir W.W.Hunter and Andrew Stirling considered the facts related in Madala Panji as base. The Madala Panji was traditionally written on a year-to-year basis.
In 1949 a new chapter opened in the history of Odisha with the excavation at Sisupalgarh conducted by B.B. Lal. A fort with impressive gateways led historians to identify it with Kalinganagari which is assumed as the capital city of Kharavela. The art and architecture of Khandagiri and Udayagiri added another source to the history of ancient Odisha.
The earliest coins available in Odisha are punch-marked coins which were in circulation between 4th century B.C. to 4th century A.D. These coins were profusely available in coastal eastern parts of Odisha.
The inscriptions of the Bhaumakaras provides a great deal of knowledge for the reconstruction of the history of Odisha. It is because the rule of the Bhauma-Karas (8th-9th century A.D.) forms glorious epoch in the annals of Odishan history.
The most valuable of the foreign accounts is that of the Chinese pilgrim Hiuen Tsang who visited Odisha in 638-39 AD. His writings have been made available to us as ‘On Yuan Chwang’s Travels’ by T. Watters, ‘Life of Hiuen Tsang’ by Hwuie and ‘Records of the Buddhist World’.
The Mahabharata makes the earliest reference to Kalinga and Odra. The Mahabharata mentions about this land and its sacred river Vaitarani and Goddess Viraja.