The most authentic source of Mauryan history is the epigraphical evidence. The edicts of Ashoka are the oldest, the best preserved and the most precisely dated epigraphic records of India. The inscriptions are engraved on rocks, boulders, cave walls and pillars of stone. The inscriptions of Ashoka are of two kinds -the smaller group consists of declaration of the king as a lay Buddhist to his church. These describe his own acceptance of Buddhism and his relationship with the Samgha. The second group of important inscriptions consists of Major and Minor rock edicts and the pillar edicts.
They describe his famous policy of Dhamma. These inscriptions were installed in prominent places either near towns or on important trade and travel routes or in the proximity of religious centres and places of religious importance.