Allahabad is a historian's paradise. History lies embedded everywhere, in its fields, forests and settlements. Forty-eight kilometres, towards the southwest, on the placid banks of the Jamuna, the ruins of Kaushambi, capital of the Vatsa kingdom and a thriving center of Buddhism, bear silent testimony to a forgotten and bygone era. On the eastern side, across the river Ganga and connected to the city by the Shastri Bridge is Jhusi, identified with the ancient city of Pratisthanpur , capital of the Chandra dynasty. About 58 kilometres northwest is the medieval site of Kara with its impressive wreckage of Jayachand's fort. Sringverpur, another ancient site discovered relatively recently, has become a major attraction for tourists and antiquarians alike.

Allahabad is an extremely important and integral part of the Ganga Yamuna Doab, and its history is inherently tied with that of the Doab region, right from the inception of the town.

The city was known earlier as Prayaga - a name that is still commonly used.

When the Aryans first settled in what they termed the Aryavarta, or Madhydesha, Prayag or Kaushambi was an important part of their territory. The Vatsa (a branch of the early Indo-Aryans) were rulers of Hastinapur, and they established the town of Kaushambi near present day Allahabad . They shifted their capital to Kaushambi when Hastinapur was destroyed by floods.

In the times of the Ramayana, Allahabad was made up of a few rishis' huts at the confluence of the rivers, and much of what is now central/ southern Uttar Pradesh was continuous jungle. Lord Rama, the main protagonist in the Ramayana, spent some time here, at the Ashram of Sage Bharadwaj, before proceeding to nearby Chitrakoot.

The Doaba region, including Allahabad was controlled by several empires and dynasties in the ages to come. It became a part of the Mauryan and Gupta empires of the east and the Kushan empire of the west before becoming part of the local Kannauj empire which became very powerful.