Chandragupta seems to have usurped the Magadhan throne, overthrowing the Nandas, in 321 bc (324, 323 and 320 bc have also been suggested by some scholars). Some identify 'Mauryas' with the Morieis tribe mentioned by the Greeks.
A Brahmanical text states that Chandragupta was born of 'Mura', a shudra woman in the Nanda court ('Mura' is also taken to be the mother or grandmother of Chandragupta and the wife of a Nanda king).
Some others represent the Mauryas as kshatriyas-medieval epigraphs represent them as kshatriyas of the solar race-and some Buddhist writers refer to them as the ruling clan of Pipphalivana (situated probably between Rummindei in the Nepalese Terai and Kasai, Gorakhpur district in Buddha's time).
According to Romila Thapar, "Chandragupta belonged to the Moriya tribe, but his caste was low, the family apparently being Vaishyas".
There are indications that rebellions were organised against Greek rule and that Greek colonies and garrisons established in the north-west of India were restive. A chief, Damaraxus, is said to have started a rebellion at Kandahar when Alexander was still at Taxila.
The satrap, Nicanor, was murdered by the Asvakayanas even when Alexander was in the Punjab region. The fight against Greek rule was probably carried on by Chandragupta during the two years 325-323 bc. According to references in the accounts of Plutarch and Justin, Chandragupta met Alexander.
Details of Chandragupta's next conquest, the one over the Nandas, are lacking. He is said to have taken advantage of the unpopularity of the Nanda rule and with the conquest brought a very large part of India under his control.
Chandragupta brought the Ganges valley under his control and moved towards the north-west where the Greek Seleucid dynasty was holding the region lying west of the Indus. It was in 305 bc, however, that Chandragupta started a campaign against Seleucus Nikator.
Chandragupta seems to have been victorious, for peace was concluded and Seleucids gave up eastern Afghanistan, Baluchistan and the region west of Indus for 500 elephants.
The Maurya Empire thus expanded its territory. The empire built up by Chandragupta included Bihar and large portions of
Orissa and Bengal as also of western and northwestern India. Chandragupta or his son extended the empire as far as present day Karnataka, parts of Maharashtra and Andhra Pradesh. North-eastern India, however, was outside the Mauryan Empire.
Jaina texts state that Chandragupta embraced Jainism. He abdicated his throne to his son and, as an ascetic, reached South India with some monks. There he died by starvation as recommended in Jaina tenets.
Greek sources show that the first Mauryan king continued to perform sacrificial rites and he took delight in hunting (alluded to in the eighth Asokan rock edict). But in his last days, he could well have shown an inclination towards Jainism. The Jaina texts are very positive about it.
Tradition states that a brahman, Chanakya (Kautilya), played an important role in establishing Chandragupta as a ruler and strengthening his powers. The ninth-century drama of Visakhadatta, Mudrarakshasa, describes the tactics Chanakya recommended to Chandragupta to fight and overcome enemies.
Bindusara (period of reign probably 300 or 299 bc - 273 or 272 bc) succeeded his father Chandragupta to the throne in 299 bc. It is not certain whether or not he made any conquests, but Bindusara (or ' amitraghatd slayer of foes) seems to have kept father's empire intact.
Scholar K.A. Nilakanta Sastri is among those who strongly hold this view. Actually, from the classical accounts or Buddhist sources, little can be known about this king and-the conclusions made about him are based mostly on traditions.
But Romila Thapar states in A History of India, Vol. I that "Bindusara campaigned in the Deccan, extending Mauryan control in the peninsula as far south as Mysore."
The author of Arya-Manjusri Mulakalpa and Hemachandra hint that Chanakya continued as a minister to Bindusara as well. The Divyavadam mentions that Bindusara suppressed a revolt at Taxila by sending his son Asoka to deal with the rebellion.
Asoka served as his viceroy at Ujjain while his eldest brother, Sumana (Susima), served as viceroy at Taxila. There are references to a visit to Bindusara's.