The cult of Lord Jagannath is so old that no one can provide the statement in this regard properly. Our tradition indicates the view boldly that the Cult of Lord Jagannath is as old as human civilization. The scholars quote a verse from Rig-Veda "Addo Yaddaru Plavate" - Which indicates that the history of Lord Jagannath dates back to the age of Rig-Veda itself.
History opines that the present temple of Lord Jagannath has been built very shortly. The historians of Odisha are all apparently in this conclusion that the present temple of Lord Jagannath at Puri has been built by Anagabhima Deva, the wonthy descendant of the king Chodaganga Deva, the founder of Ganga dynasty in Odisha in 12th Century A.D. It does not mean that the temples of all other deities by which the Jagannath temple is surrounded are equally old. Some of them might have been built very recently.
But the origial temple of Lord Jagannath repaired as well as reconstructed by the King Jajati Keshari, one of the famous emperors of Keshari dynasty in Odisha perhaps in fourteenth century A.D. Also it can be traced from the hostory that the cult of Lord Jagannath is originally of the 2nd century B.C. when Kharavela was the emperor of Kalinga, another old name of Odisha. The historic Elephant Cave (Hati Ghumpha) inscription of this emperor on the top of Udayagiri (a hill) near to Bhubaneswar indicates regarding the Jinashan which is identified with Lord Jagannath. But the reliable as well as historical matter is available from the 9th century.
There was the influence of Buddhism on the cult of the Savara deity.Buddhism was established in Odisha after Ashok.Who are the three deities,Jagannath,Balabhadra and Subhadra?They can not be Ram,Laxman and Sita because Subhadra is sister and Balabhadra is elder brother.The three deities have a lot of similarity with the Buddhist triad: Buddha,Dharma and Sangha.Jagannath is Buddha,Balabhadra stands for Sangha.Is n't it necessary to have an elderly person to run a Sangha(Monostic order)? Subhadra is the symbol of Dharma.Sauvada is Dharma in Buddhist philosophy and is perceived in the feminine form.Further,there are not three,but four deities-Chaturdha Murti-including Sudarsana Chakra.What does he stand for?Chakra occurs as a symbol in all religions.The wheel in Buddhism is the symbol of religious essence.The ideas which Buddha preached to the five ascetics at Sarnath are treated as central to the establishment of Dharma Chakra.In the Hindu religion,Chakra is the weapon of Vishnu.What is the shape of the Chakra?It is "Akhanda Mandalakaram"-Unbroken like a sphere.It has neither a beginning nor an end.Therefore it is Sanatana Dharma,eternal religion.No one can say when religion began and when it would end.
There is also the Buddhist influence on the Ratha Yatra.The custom of taking the idol and the Tooth of Buddha round the city on a chariot has been prevalent from the days of Fahien,the Chinese traveller.Some say that "Indra Ratha" appears in the Vedas,and that the Gita speaks of the body as chariot and Soul as charioteer-"Atmanam Rathinam Vidhi."But these have no relationship with Ratha Yatra.It was after all quite usual for the kings and the warriors to move on chariots.We first find the mention of Gods riding on Chariots in the history of Buddhist religion.