According to Plutarch, at the time of the Battle of the Hydaspes, the Nanda Empire's army numbered 200,000 infantry, 80,000 cavalry, 8,000 chariots, and 6,000 war elephants, which discouraged Alexander's men and prevented their further progress into India: As for the Macedonians, however, their struggle with Porus blunted their courage and stayed their further advance into India. Chandragupta's reign was a time of great social and religious reform in India.

Later Ptolemy II Philadelphus, the ruler of Ptolemaic Egypt and contemporary of Ashoka the Great, is also recorded by Pliny the Elder as having sent an ambassador named Dionysius to the Maurya court. In Greek and Latin accounts, Chandragupta is known as Sandrokottos and Androcottus. After having made a treaty with him [Sandrakotos] and put in order the Orient situation, Seleucos went to war against Antigonus.

Geni requires JavaScript! Chandragupta was influenced to accept Jainism by the sage Bhadrabahu; he abdicated his throne to spend his last days at the Shravana Belgola, a famous religious site in southwest India, where he fasted to death. Regardless, in the ensuing war, Chandragupta faced off against Bhadrasala, the commander of Dhana Nanda's armies. After this incident, Chanakya began to persuade his disciple Chandragupta of the need to build an empire that could protect Indian territories from foreign invasion.

It is generally thought that Chandragupta married Seleucus's daughter to formalize an alliance. On the other hand, the same play describes the Nandas as of Prathita-kula, i.e. In order to defeat the powerful Nanda army, Chandragupta needed to raise a formidable army of his own. Plutarch and other Greco-Roman historians appreciated the gravity of Chandragupta Maurya's conquests. He then married Helena, a Greek Princess at the age of 40. After Alexander's death in 323 BCE, Chandragupta turned his attention to Northwestern South Asia (modern Pakistan), where he defeated the satrapies (described as "prefects" in classical Western sources) left in place by Alexander (according to Justin), and may have assassinated two of his governors, Nicanor and Philip. (The Sakya line of Kshatriyas is considered to be the lineage of Gautama Buddha, and Ashoka Maurya billed himself as "Buddhi Sakya" in one of his inscriptions.). https://en.wikipedia.org/wiki/Chandragupta_Maurya.

As soon as the forces, therefore, of all the confederates were united, a battle was fought, in which Antigonus was slain, and his son Demetrius put to flight. Chandragupta Maurya is a pivotal figure in the history of India. Justin describes the humble origins of Chandragupta, and explains how he later led a popular uprising against the Nanda king.

On the other hand, Pliny, who also drew from Megasthenes' work, gives even larger numbers of 600,000 infantry, 30,000 cavalry, and 9,000 war elephants: But the Prasii surpass in power and glory every other people, not only in this quarter, but one may say in all India, their capital Palibothra, a very large and wealthy city, after which some call the people itself the Palibothri,--nay even the whole tract along the Ganges. Due to its unified structure, the empire developed a strong economy, with internal and external trade thriving and agriculture flourishing. Chandragupta Maurya (IAST: Candragupta Maurya, c. 321-c. 297 BCE) was the founder of the Maurya Empire and the first emperor to unify most of Greater India into one state.

Seleucus I Nicator, a Macedonian satrap of Alexander, reconquered most of Alexander's former empire and put under his own authority the eastern territories as far as Bactria and the Indus (Appian, History of Rome, The Syrian Wars 55), until in 305 BCE he entered into conflict with Chandragupta: Always lying in wait for the neighboring nations, strong in arms and persuasive in council, he acquired Mesopotamia, Armenia, 'Seleucid' Cappadocia, Persis, Parthia, Bactria, Arabia, Tapouria, Sogdia, Arachosia, Hyrcania, and other adjacent peoples that had been subdued by Alexander, as far as the river Indus, so that the boundaries of his empire were the most extensive in Asia after that of Alexander. Chandragupta was born into a family left destitute by the death of his father, chief of the migrant Mauryas, in a border fray. It is noted in the Chandraguptakatha that Chandragupta and Chanakya were initially rebuffed by the Nanda forces.

According to Bharatendu Harishchandra's translation of the play, his father was the Nanda king Mahananda and his mother was a barber's wife named Mora, hence the surname Maurya. A princess of Nanda … Bindusara's son Ashoka became one of the most influential rulers in India's history due to his extension of the Empire to the entire Indian subcontinent as well as his role in the worldwide propagation of Buddhism.
At the time of Alexander's invasion, Chanakya was a teacher in Takshasila. The Greek diplomat Megasthenes, who visited the Mauryan capital Pataliputra, is an important source of Mauryan history. Plutarch reports that he met with Alexander the Great in Punjab, and that he viewed the ruling Nanda Empire in a negative light: Androcottus, when he was a stripling, saw Alexander himself, and we are told that he often said in later times that Alexander narrowly missed making himself master of the country, since its king was hated and despised on account of his baseness and low birth. There was a growth in culture which derived its inspiration from the Achaemenids and the Hellenistic world. — Justin, Historiarum Philippicarum libri XLIV, XV.4.19, Conquest of Seleucus' eastern territories. In both art and architecture, the Mauryan empire constituted a landmark. This reinforces Justin's contention that Chandragupta had a humble origin.