The Somavamsis, other wise known as Panduvamsis, ruled over Odisha from the middle of the ninth century A.D. to the early part of the twelfth century A.D. Initially, in the seventh and eighth centuries A.D., they ruled over a piece of territory, known as Dakhina Kosal or South Kosala (corresponding to the Raipur and Bilaspur districts of Madhya Pradesh and the Sambalpur and Kalahandi districts of Odisha). Sirpur, a place, situated in the Raipur district, was the capital of-the Somavamsis of south Kosala. Udayana was the founder of this dynasty.
Tivaradeva, the fourth king of the line, was its most powerful ruler. He established his sway over the whole of Kosala. In the west he extended his territory as far as the Vindhyas. But in the east his efforts to bring Kangoda within his political sway failed. Tivaradeva ruled from 700 A.D. to 725 A.D. At the dawn of the ninth century A D., Sornavamsi kingdom was invaded by Govindalll, the Rastrakuta king. For sometime, the Somavamsis remained under the hegemony of the Rastrakutas. After the death of Govinda-III in 814 A.D the Somavamsis could emancipate themselves from the hegemony of the Rastrakutas. But, there after they were exposed to the threats of another power, the Kalachuris of Ratnapur (a place in the Bilaspur district of Madhya Pradesh). By the middle of the ninth century A.D. the Somavamsis were seeking eastward expansion most probably because of the Kalachuri menace. The last known king of Somavamsis of south Kosal was Balarjuna Sivagupta who died in 810 A.D. After him, there is a genealogical gap for more than half a century. With the emergence of Janrnejaya-l in the last quarter of the ninth century A.D. we get a regular genealogical line of the Sornavarnsis up to the beginning of the twelfth century A.D. The inscription of Janmejaya-I, the builder of the Somavamsi power in Odisha, mention Sivagupta as his predecessor. The Somavamsi rulers of Odisha were alternatively using two titles – Mahabhavaupta and Mahasivagupta. Besides these facts the same dynastic name strongly suggests that Janmejaya-I was the descendant of the Somavamsis of south Kosala.
There is no such written record regarding the complete history of the Somavamsi rulers and their achievements. However, we get some information from the following inscriptions. The Banda Copper plates of Tivaradeva, Adhavara plates of Mahanannararaja Banda plates of Mahasivagupta; Patna, Kalibhana and other copper plates of Janrneiaya Cuttack, Nibinna and Patna plates of Yayati I; Kalanjar stone inscription, Arang store inscription, Sirpur stone inscription and other inscriptions of the rulers of this dynasty ar the contemporary Bhanja, Bhauma-Kara, Ganda and other inscriptions throw a good dea of light on the achievements of the rulers of this dynasty.