The Seleucid–Mauryan War was a confrontation between the Seleucid and Mauryan empires that took place sometime between 305 and 303 BCE, when Seleucus I Nicator of the Seleucid Empire crossed the Indus River into the former Indian satrapies of the Macedonian Empire, which had been conquered by Emperor Chandragupta Maurya of the Maurya Empire.
The confrontation resulted in a dynastic marriage-alliance between Seleucus and Chandragupta, the gift of war elephants to Seleucus, and the transferring of control over the Indus Valley region and (possibly) part of Afghanistan to Chandragupta. The alliance freed Seleucus to turn his attention toward his rivals in the west, while Chandragupta secured control over the areas that he had sought, the Maurya Empire emerging as the dominant power of the Indian subcontinent.
Background
In the wake of Alexander's Indian campaign, Chandragupta Maurya led a successful revolt from north-western India against the Nanda Dynasty, rulers at the time of the Gangetic Plain, establishing himself as Emperor of Magadha around 321 BC. He fought the empire for eleven years with successful guerrilla campaigns, and captured the Nanda capital of Pataliputra. This led to the fall of the empire and the eventual creation of the Maurya Empire with Chandragupta Maurya as its emperor.
The Persian provinces in what is now modern Afghanistan, together with the wealthy kingdom of Gandhara and the states of the Indus Valley, had all submitted to Alexander the Great and become part of his empire. When Alexander died, the Wars of the Diadochi ("Successors") split his empire apart; as his generals fought for control of Alexander's empire. In the eastern territories one of these generals, Seleucus I Nicator, was taking control and was starting to establish what became known as the Seleucid Empire. According to the Roman historian Appian, History of Rome, Seleucus was
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. The whole region from Phrygia to the Indus was subject to Seleucus.
The Roman historian Justin described how Sandrocottus (Greek version of Chandragupta's name) assassinated Greek governors and established an oppressive regime "after taking the throne":
"India, after the death of Alexander, had assassinated his prefects, as if shaking the burden of servitude. The author of this liberation was Sandracottos [Chandragupta], but he had transformed liberation in servitude after victory, since, after taking the throne, he himself oppressed the very people he has liberated from foreign domination."
Confrontation
Details of the conflict are lacking, and the only sources mentioning the confrontation between Seleucus and Chandragupta are a few references by Strabo, Appian, Plutarch, and Justin. According to Appian,
[Seleucus] crossed the Indus and waged war with Sandrocottus [Maurya], king of the Indians, who dwelt on the banks of that stream, until they came to an understanding with each other and contracted a marriage relationship. Some of these exploits were performed before the death of Antigonus and some afterward.
— Appian, History of Rome, The Syrian Wars
While numerous authors interpret the Greek sources as describing a Mauryan victory, others are more cautious, and stay close to what the Greek sources say. The details of the conflict, and if there was in fact a pitched battle, are unknown, and Jansari warns that "there are very little details about the battle or skirmish they fought, and that none of the ancient authors depicted either Seleucus or Chandragupta as the clear victor of this battle. This lack of information about the encounter and the ensuing treaty means that it is impossible to reconstruct them." Wheatley and Heckel suggest that the degree of friendly Maurya-Seleucid relations established after the war implies that the hostilities were probably "neither prolonged nor grievous".
Dynastic marriage-alliance
The confrontation was followed by a dynastic marriage-alliance, briefly mentioned by, or alluded to, by Greco-Roman authors Strabo (64 or 63 BCE – c. 24 CE) XV 2,9, Plutarch (1st c. CE), Justin (2nd c. CE), and Appian (2nd c. CE) 'Syr. 55. According to Jansari, Strabos and Plutarch may have drawn information from the same source, possibly Megasthenes. No Indian sources record the events, and Jansari warns that "the dependence on a small group of sources from only one literary tradition necessitates a cautious approach to these texts and the events they describe."
Three terms are recorded by these ancient sources. Seleucus Nicator seems to have ceded territories to Chandragupta, and received war elephants from Chandragupta Maurya, which subsequently influenced the Wars of the Diadochi in the west. Seleucus and Chandragupta also agreed to a marriage alliance, probably the marriage of Seleucus' daughter to Chandragupta.
Overview of the alliance
Strabo mentions the exchange of elephants and territory as part of the dynastic marriage-alliance. In his Geographica, composed about 300 years after Chandragupta's death, he describes a number of tribes living along the Indus, and then states that "The Indians occupy [in part] some of the countries situated along the Indus, which formerly belonged to the Persians":
The geographical position of the tribes is as follows: along the Indus are the Paropamisadae, above whom lies the Paropamisus Mountains: then, towards the south, the Arachoti: then next, towards the south, the Gedroseni, with the other tribes that occupy the seaboard; and the Indus lies, latitudinally, alongside all these places; and of these places, in part, some that lie along the Indus are held by Indians, although they formerly belonged to the Persians. Alexander [III 'the Great' of Macedon] took these away from the Arians and established settlements of his own, but Seleucus Nicator gave them to Sandrocottus [Chandragupta], upon terms of intermarriage and of receiving in exchange five hundred elephants.
Jansari notes that "them" refers to "territories previously held by Alexander, but it is not specified which these were."
V.A. Smith (1914):
...the cession made in 303 b.c. by Seleukos Nikator to Chandragupta Maurya included provinces of the Paropanisadae (Kabul), Aria (Herat), Arachosia (Kandahar), and probably Gedrosia (Makran), or a large part of that satrapy.
Kosmin summarizes those sources as follows, cautiously interpreting which territories may have been transferred:
The ancient historians Justin, Appian, and Strabo preserve the three main terms of what I will call the Treaty of the Indus:(i) Seleucus transferred to Chandragupta's kingdom the easternmost satrapies of his empire, certainly Gandhara, Parapamisadae, and the eastern parts of Gedrosia, and possibly also Arachosia and Aria as far as Herat.(ii) Chandragupta gave Seleucus 500 Indian war elephants.(iii) The two kings were joined by some kind of marriage alliance (ἐπιγαμία οι κῆδος); most likely Chandragupta wed a female relative of Seleucus.
Jansari notes that, in the 20th century, diverging views on Chandragupta have developed between western academics and Indian scholars. While westerners tend to take a reserved view on Chandragupta's accomplishments, Indian authors have portrayed Chandragupta as a very successful king who established the first Indian nation.
Transferred territories
Gedrosia (Baluchistan)
V.A. Smith (1914), Early History of India,:
The satrapy of Gedrosia (or Gadrosia) extended far to the west, and probably only the eastern part of it was annexed by Chandragupta. The Malin range of mountains, which Alexander experienced such difficulty in crossing, would have furnished a natural boundary.
Tarn limits the ceded part of Gedrosia to the territory east of the Porali Hingol) river, referring to Eratosthenes (c.276 BC – c.195/194 BCE), who states (in Tarn words) that
Alexander [...] took away from Iran the parts of these three satrapies which lay along the Indus and made of them separate [...] governments or province; it was these which Seleucus ceded, being districts predominantly Indian in blood. In Gedrosia the boundary is known: the country ceded was that between the Median Hydaspes (probably the Purali) and the Indus."
With regard to Gedrosia, more recent authors mention either "Gedrosia," which gives the impression that Baluchistan as far as Iran was hand over, or '[the eastern] part of Gedrosia'. According to Thapar (1963), referring to Smith (1914), History of India,
"Certain areas in the north-west were acquired through the treaty with Seleucus. There is no absolute certainty as to which these areas were and it has been suggested that the territory ceded consisted of Gedrosia, Arachosia, Aria [modern-day Herat], and the Paropamisadae."
In History of Early India, also from 1963, Thapar writes that "Some Seleucid territories that today would cover eastern Afghanistan, Baluchistan and Makran were ceded to the Maurya."
According to Kosmin, Seleucus "certainly" transferred "the eastern parts of Gedrosia." Thomas Trautmann includes the Makran Coast, referring to Smith (1924), and taking the Ashokan Edict of Kandahar as a validation for a maximum interpretation of Strabo. Smith actually takes the Malin range, east of the Makran coast, as the western limit, The validation by the Ashokan edicts is questioned by Coningham & Young and "a growing number of researchers," as the Ashokan edicts may rather point to the maximum extent of contact, and not of institutionalized control.
Coningham & Young also question the extent of control over the lower Indus Valley, following Thapar, noting that this may have been an area of peripheral control. Raymond Allchin also notes the absence of major cities in the lower Indus Valley.
Paropamisadae (Gandhara and Kabul) and Arachosia (Kandahar)
According to Tarn, "the Paropamisadae itself was never Chandragupta's." Tarn, writing in 1922 before the discovery of the edicts of Ashoka in Kandahar and Laghman Province in the 1930s-60s, limits the exchanged territory to the Indus Valley. According to Tarn, the limit followed the Kunar river, east of Kabul and ending in Jalalabad, further south along the watershed, and ending at the Hingol river.
Kosmin writes that Seleucud "certainly" ceded Gandhara and Parapamisadae (this includes Gandhara), but "possibly" also Arachosia. Trautmann includes most of Afghanistan, including Herat, and Pakistan, noting that this extent has been doubted. He refers to Smith, stating that Smith "convincingly supported the veracity of the territorial cession," and arguing that the Ashokan inscription in Gandhara "confirmed the accuracy of the ancient testimony."
Coningham & Young question the extent of control over eastern Afghanistan, noting that "a growing number of researchers would now agree that the Ashokan edicts may have represented 'an area of maximum contact rather than streamlined bureaucratic control'."
Aria (Herat)
The acquisition of Aria (modern Herat) is disputed. Smith included a large part of Aria, referring to Strabo and Pliny. Strabo XV, 1, 10:
the Indus River was the boundary between India and Ariana, which latter was situated next to India on the west and was in the possession of the Persians at that time; for later the Indians also held much of Ariana, having received it from the Macedonians.
Pliny the Elder (23/24–79 CE):
Most geographers, in fact, do not look upon India as bounded by the river Indus, but add to it the four satrapies of the Gedrosia, the Arachotë, the Aria, and the Paropamisadë, the River Cophes [Kabul River], thus forming the extreme boundary of India. According to other writers, however, all these territories, are reckoned as belonging to the country of the Aria.
Smith reads Strabo XV 1,10 as implying that "Strabo informs us that the cession included a large part of Ariane." He further argues that Pliny, in his treatment of the borders of India, when referring to various authors who "include in India the four satrapies of Gedrosia, Arachosia, Aria, and the Paropanisadae," this
...must have been based on the fact that at some period previous to A.D. 77, when his book was published, these four provinces were actually reckoned as part of India. At what time other than the period of the Mauryan dynasty is it possible that these provinces should have formed part of India?