Little is known about Chandragupta Maurya's origins. For two centuries historians have been attempting to establish the chronology of early India, which includes the question of whether Chandragupta is the figure known in ancient Greek texts as Sandrokottos. Philologist William Jones began systematic study of early India during the late 18th century. Nineteenth- and early twentieth-century Indologists were reluctant to believe traditional Indian accounts of the past. Subsequent scholars accepted the identity of Sandrokottos with Chandragupta Maurya. James Prinsep deciphered Brāhmī script and was able to read the inscriptions of Piyadassin (Ashoka). George Turnour found in the Ceylonese chronicles that Piyadassin was used as an alternate name for Ashoka, grandson of Chandragupta Maurya. An inscription with Piyadassin as a name for Ashoka was not found until Turnour's era. In 1838 Prinsep found five names of Yona kings in Ashoka's inscriptions and identified them as the five Greek kings, successors of Alexander in the third century BC, who were contemporaries of Ashoka.
"The kings before and after Chandragupta Maurya were Dhana Nanda and Bindusara. The kings before and after Chandragupta Gupta were Chandramas and Samudragupta. The phonetic similarity is quite apparent for Chandragupta Gupta and not Maurya." Strabo identifies both Chandragupta and his son Bindusara (Amitraghata; Slayer of Enemies), and connects them to the third-century ambassadors Megasthenes and Deimakos sent to their courts. "Both of these men were sent ambassadors to Palimbothra (Pataliputra): Megasthenes to Sandrocottus ("Chandragupta"), Deimakos to Allitrochades ("Amitraghata") his son". (Strabo II, I, 9) Plutarch also directly connects Chandragupta to Alexander himself: "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." Plutarch 62-3.
Greek records, however, are silent about figures such as Chanakya and Ashoka (whose kingdom was larger than Chandragupta's). They are not said to clearly mention Buddhist monks (common in the Maurya era), but Greek accounts of shramanas are thought to correspond to them. An inscription on a Greek tomb is reported to read, "Here lies Indian Sramanacharya, Shakya monk from Bodh Gaya". However, in 1000 BC the Greeks did not yet use an alphabet and the inscription has been dated to 10 CE. Nicolaus of Damascus wrote an account of a diplomatic mission sent by an Indian king "named Pandion (Pandyan kingdom) or, according to others, Porus" to Caesar Augustus about 13 CE who met with the ambassador at Antioch. The mission had a diplomatic letter in Greek, and one of its members was a Sarmano (Greek: Σαρμανο) who immolated himself in Athens to demonstrate his faith. The event was cited by Strabo and Dio Cassius. A tomb was made for the sarmano (still visible at the time of Plutarch), which read "ΖΑΡΜΑΝΟΧΗΓΑΣ ΙΝΔΟΣ ΑΠΟ ΒΑΡΓΟΣΗΣ" (Zarmanochēgas Indos apo Bargosēs; "The sramana master from Barygaza in India").
The names of contemporary kings found on Ashokan inscriptions are said to include Antiyoka and Tulamaya. It is thought that the edict in question mentions Western Greek kings during the time of Ashoka: "Now it is conquest by Dhamma that Beloved-of-the-Gods considers to be the best conquest. And it (conquest by Dhamma) has been won here, on the borders, even six hundred yojanas (4,000 miles) away, where the Greek king Antiochos (Antiyoka) rules, beyond there where the four kings named Ptolemy, Antigonos, Magas and Alexander rule, likewise in the south among the Cholas, the Pandyas, and as far as Tamraparni." In the Gandhari version, Antiochos is called "Antiyoko nama Yona-raja" (literally "The Greek king by the name of Antiochos"), "beyond whom live the four other kings: "param ca tena Atiyokena cature rajani Turamaye nama Antikini nama Maka nama Alikasudaro nama" ("And beyond Antiochus, four kings by the name of Ptolemy, Antigonos, Magas and Alexander").
According to Greek accounts Xandrammes was deposed by Sandrokottos, son of Sandrokottos. Chandragupta Maurya had opposed Dhanananda of the Nanda dynasty; his son was Bindusara. These names (Dhanananda and Bindusara) are dissimilar to the names Xandrammes and Sandrocyptus in the Greek accounts. However, as in the case of Amitraghata (Bindusara), Greek sources mention secondary (Sanskritic) names for Indian kings. The Greek accounts contain statements from Greek and Roman writers from the fourth century BC to the second century CE. None mention Kautilya or Ashoka. Kautilya, according to tradition, helped Chandragupta to the throne. Ashoka's empire was larger than Chandragupta's. Colebrook has pointed out that the Greek writers did not say anything about the Buddhist Bhikkhus (although that was the predominant religion of the time) due to Ashoka's patronage. Herodotos, in his Histories, about 420 BC, mentions ascetics in the Punjab.
The conclusive and most ancient evidence of Chandragupta's kshatriya origin is provided in a book by Chanakya explaining the preference for a poor kshatriya (Chandragupta) over an adharmic (Nanda) king. Chanakya describes himself as a protector of religion because he destroyed the Nanda and gave the empire to the kshatriya Chandragupta.
The Puranas are clear on the Sudra(barber) lineage of Chandragupta Maurya. The Matsya Purana describes a King Moru, who will restore Sudra(barber) rule in India and found the Morya (or Maurya) dynasty (which would be followed by the Shunga Empire). The Vishnu Purana also mentions King Moru, who would reestablish Sudra(barber) rule in India by destroying the shudra Nanda. The Vayu Purana states that the Yuga Morya dynasty would restore the Suryavansha in India and be followed by the Shunga Empire. The medieval commentator Ratnagarbha, in his commentary on the Vishnu Purana, concludes that Chandragupta is the son of a Nanda emperor. However, the Vishnu Purana maintains that Chandragupta has link to the Nanda kings; a militant Brahmin (Chanakya) would protect dharma (religion), uprooting the Shudra Nanda with the help of a royal man(Chandragupta) with a claim to be emperor of India.
Other literary traditions imply that Chandragupta was raised by peacock-tamers (Sanskrit: Mayura-Poshakha), which earned him the Maurya epithet. Buddhist and Jain traditions attest the connection between the Moriya (Maurya) and Mora, or Mayura (Peacock). While Buddhist tradition describes him as the son of the chief of the peacock clan (Moriya kshatriya), Jain tradition refers to him as the maternal grandson of the headman of the village of peacock tamers (Moraposaga). This view suggests a humble background for Chandragupta; the same tradition also describes Nanda as the son of a barber and a courtesan. The pillar of Ashoka in Nandangarh has the figure of a peacock (repeated in many sculptures of Ashoka at Sanchi) on its bottom. According to Turnour, Buddhist tradition also attests a connection between Moriya and Mora (or Mayura, or peacock). Aelian informs us that tame peacocks were kept in the parks of the Maurya palace at Pataliputra. Scholars such as Foucher do not regard these birds as a symbol of the Maurya dynasty, preferring to imagine an allusion to the Mora Jataka. In addition to peacocks, other birds (such as pheasants and parrots) and a variety of fishes were also kept in the parks and pools of the Mauryas.
Other literary traditions exist in which Chandragupta belonged to the Moriyas, a kshatriya (warrior) clan of the small, ancient republic of Pippalivana (located between Rummindei, in the Nepalese Tarai, and Kasia in the Gorakhpur district of Uttar Pradesh). Tradition suggests that this clan was decimated during the fourth century BC under Magadhan rule, and Chandragupta grew up with peacock-tamers, herdsmen and hunters. The Buddhist text Mahavamsa calls Chandragupta a scion of a Khattya (kshatriya) clan named Moriya (Maurya). Divyavadana calls Bindusara (Chandragupta's son) an anointed kshatriya (Kshatriya Murdhabhishikata); in the same work, Ashoka (son of Bindusara) is also called a kshatriya. The Mahaparinibbana Sutta of the Buddhist canon states that the Moriyas belonged to the kshatriya community of Pippalivana. This tradition indicates that Chandragupta had a kshatriya lineage. Plutarch confirms the kshatriya origin of Chandragupta.
The Mahavamsa connects him to the Sakya clan of Gautama Buddha, a clan which also claimed to belong to the race of Aditya. The ancient Jain text Punyashrava Katha Kosh refers to Chanragupta as kshatriya. A medieval inscription represents the Maurya clan as part of the "solar race" of kshatriyas, saying that the Maurya line sprang from Suryavamsi Mandhatri (son of prince Yuvanashva of the solar race).
Although most sources indicate that Chandragupta was of east-Indian origin, alternative theories have been proposed by scholars. Some relate Sandrocottos (or Androcottos) to Sisicottos of classical literature. Sisicottos was the ruler of Paropamise (Hindu Kush) who helped the last Persian satrap (Bessus of Bactria) against Alexander, later co-operating with the latter during the Sogdian campaigns. During Alexander's campaigns in Kabul and the Swat River valley, Prince Sisicottos helped him defeat several principalities of the Ashvakas. During a battle at the fortress of Aornos in which Alexander faced stiff resistance from the local population, Sisicottos was put in command of the strategically important fort and Arrian refers to Sisicottos the governor of Assakenoi. However, it is unclear whether Sisicottos was Sandrocottos or if they were related. J. W. McCrindle and H. R. Gupta hypothesize that "they both possibly belonged two different branches of the Ashvakas". Meri may have been another political centre of the Mor (Meros) people. The name "Moriya" (or Maurya) may have come from Mor (Koh-i-Mor; "Mor hill), the ancient Meros of classical literature in the Paropamisade region between the Kunar and Swat Rivers in the land of Ashvakas. (This name, refers to the Meru mountain of Chitral, Tirich Mir; there is also a Deva-Meru in modern Diamar). It is claimed that since Chandragupta Maurya could have belonged to Mor, he "was called Moriya or Maurya after his motherland". Spooner observes, "After Alexander's death, when Chandragupta marched on Magadha, it was with largely the Persian army (Shaka-Yavana-Kamboja-Parasika-Bahlika) that he won the throne of India. The testimony of the Mudrarakshasa is explicit on this point, and we have no reason to doubt its accuracy in matter[s] of this kind". This theory contradicts the Mudrarakshasa, which examines Malayketu's alliance with the Persians (not Chandragupta). According to the Mudrarakshasa, Malayaketu, Rakshasa (the last minister of Nanda) and his Persian allies wanted to invade Pataliputra, the capital of Chandragupta. Their alliance was undone by Chanakya, who attracted Rakshasa to the Maurya side.
Shakya was an independent state with an elective monarchy in the foothills of the Himalayas with its capital at Kapilavastu. Gautama Buddha was a member of the Shakya clan lineage and one of its kings. The Mahavamsa (II, 1–24) traces the origin of the Shakya clan to the Ikshvaku clan of Ayodhya into which Rama was born.
Shakya kshatriyas considered themselves the purest breed of kshatriya. To protect their purity they performed Gotriya (Sagotriya) marriages, which were prohibited by Hinduism. This led to a massacre by the king of Kosala. Pasenadi was the suryavanshi kshatriya king of Kosala with its capital at Sravasti. He was a Buddhist, building many monasteries. After defeating the Shakya, he asked to marry a Shakyan girl, promising that their son would be the next king of Kosala. He married Vasavkhattiya, who gave birth to a boy, Virudhaka, who became the prince of Kosala. Virudhaka overthrew Pasenadi as king of Kosala.