The establishment of Mauryan dynasty by Chandragupta Maurya in 321 BC marks a turning point in the history of early India. For the first time now, we have at our disposal a number of sources which throw better light on the history of this period.
The edicts issued by Ashoka are the most important source of information and there are at least 44 such edicts which have been found inscribed on rocks and pillars. These are composed mostly in Prakrit language and are written in Brahmi script in most of the areas. These inscriptions are also the first evidence of writing in ancient India.
As far as archaeological sources are concerned, punch-marked coins, remains of the palace of Ashoka at Kumharar and several pieces of sculptures are important.
The most important literary sources are Arthasastra of Kautilya and Indica of Megasthenes. Arthasastra is a text on statecraft, which gives advice to kings as to how to rule his land and discharge his duties. Indica is an account left by a Greek ambassador Megasthenes sent by Seleucus to the court of Chandragupta Maurya. Two Ceylonese Buddhist texts called Dipavamsa and Mahavamsa and a play called Mudrarakshas written by Visakhadatta are other valuable source books.
The founder of the Mauryan dynasty, Chandragupta Maurya (321-297 BC) inherited a large army of the Nandas, which he used to conquer almost whole of north, the north-west, and a large part of the peninsular India.
His son Bindusara (297-269 BC) succeeded him. He promoted trade and cultural interaction with Greeks, but not much is known about him.
Ashoka (269-232 BC) succeeded his father Bindusara. According to Buddhist traditions he came to throne after killing his 99 brothers, but such stories cannot be trusted without confirmation from other sources. Ashoka fought a major war with Kalinga around 261 BC in which large number of people were killed or imprisoned. Perhaps this bloodshed moved his heart and he decided to abandon the policy of military expansion and declared that he would in future favour dhammaghosha (drum of dhamma) than bherighosha (war drum).
He spent the rest of his life in promoting and spreading the policy of Dhamma. However, his successors could not keep the empire integrated and it completely disappeared after the last king Brihadaratha was assassinated by his military chief Pushyamitra Sunga around 187 BC.