The term Thrissur is the abbreviated anglicized form of the Malayalam word "THRISSIVAPERUR" which means the town of the "SACRED SIVA". The town is built on an elevated ground, at the apex of which is the famous "VADAKKUMNATHAN" Temple. A place of great antiquity, Thrissur was also known as "VRISHABHADRIPURAM" and "TEN KAILASAM" in ancient days.

From ancient times, Thrissur District has played a significant part in the political history of south India. The early political history of the District is interlinked with that of the Cheras of the Sangam age, who ruled over vast portions of Kerala with their capital at Vanchi. The whole of the present Thrissur District was included in the early Chera Empire.

The District can claim to have played a significant part in fostering the trade relations between Kerala and the outside world in the ancient and medieval period. It can also claim to have played an important part in fostering cultural relations and in laying the foundation of a cosmopolitan and compose culture in this part of the country. Kodungalloor which had the unique distinction of being the "Primum Emporium India", also belongs to the signal honour of having first given shelter to all the three communities which have contributed to the prosperity of Malabar'. These three communities are the Christians, the Jews and the Muslims.

The history of Thrissur District from the 9th to the 12th centuries is the history of Kulasekharas of Mahodayapuram and the history since 12th century is the history of the rise and growth of Perumpadappu Swarupam. In the course of its long and chequered history, the Perumpadappu Swarupam had its capital at different places.

We learn from the literary works of the period that the Perumpadappu Swarupam had its headquarters at Mahodayapuram and that a number of Naduvazhies in Southern and Central Kerala recognized the supremacy of the Perumpadappu Moopil. The Perumpadappu Moopil is even referred to as the "Kerala Chakravarthi" in the "Sivavilasam" and some other works.
One of the landmarks in the history of the Perumpadapu Swarupam is the foundation of a new era called Pudu Vaipu Era. The Pudu Vaipu Era is traditionally believed to have commenced from the date of which the island of Vypeen was thrown from the sea.