A historian needs source material to reconstruct the past. But sources themselves do not reveal the past. They need interpretation and the historian makes them speak. In fact the historian is expected to track the source, read texts, follow clues, ask relevant questions, cross check evidence to offer meaningful explanation.
For example, in 1826 Charles Masson noticed the high walls and towers of an old settlement in Harappa Village of western Punjab (now in Pakistan), and five decides later Sir Alexander Cunningham collected some seals from the site, but it took archaeologist John Marshall another fifty years to identify the oldest civilization in the Indus region.
Another example regarding the historian’s task to cross check (corroborate) different types of evidence. Nowhere in the sources pertaining to king Harsha (seventh century AD) do we find a mention of his defeat at the hands of Chalukya ruler Pulakesin II. But the inscriptions of Pulakesin II claim a victory over Harsha. In this case it is obvious that Harsha’s biographer Bana Bhatt who wrote Harshacharita deliberately did not mention the defeat of his patron.
The literal meaning of the itihasa is ‘thus it was’ and it is translated as ‘history’. There was a time when only written records were acknowledged as authentic source of history. Written material could be verified, cited and cross-checked. Oral evidence i.e myths and folk songs was never considered a valid source. Earlier historians used myth, fiction and oral traditions in a limited way on account of their lack of authenticity and verifiability. But today these unconventional sources are being used innovatively.
Traditions and cultural traits should be studied in the light of other historical facts. For example, the Mahabharata is a story of conflict between two sets of warring cousins. One in not sure whether there was a real war as narrated in the epic. Some historians believe that the war did happen while others wait for corroborative evidence for the event .The original story was probably composed by bards known as sutas who generally accompanied Kshatriya warriors to the battlefield and recited poems in praise of victories and other achievements of their heroes. These compositions were circulated orally and preserved as part of human memory.