Shashigupta IAST: Śaśigupta was a ruler of Paropamisadae (modern north-west Pakistan and eastern Afghanistan), between the Hindu Kush mountains and Indus Valley during the 4th century BCE.^{[citation needed]} The name Shashigupta is a reconstruction of a hypothetical Indo-Aryan name, based on a figure named in ancient Greek and Roman sources as Sisikottos (Arrian), and Sisocostus (Curtius).

The root shashi is equivalent to chandra ("moon") in Indian languages. Consequently, Shashigupta is often linked to various figures known as Chandragupta in ancient Indian sources. Both names mean "moon-protected". However, there is no consensus amongst modern scholars as to which of the historical Chadraguptas, if any, may be identified with Shashigupta.

Nothing is known about early life of Shashigupta. He was presumably a military adventurer, a leader of corporation of professional soldiers (band of mercenary soldiers) whose main goals were economic and military pursuits.^{[citation needed]}

In all probability, Shashigupta was a professional soldier and led a corporation of mercenary soldier to help Persians especially Bessus, the Iranian Satrap of Bactria but once his case was lost, Shashigupta, along with band of warriors (obviously as mercenary soldiers), threw his lot with the invaders and thereafter, rendered a great help to Alexander during latter's campaigns of Sogdiana and later also of the Kunar and Swat valleys.^{[citation needed]}

In May 327 BCE, when Alexander the Great invaded the republican territories of the Alishang/Kunar, Massaga and Aornos on the west of Indus, Shashigupta had rendered great service to the Macedonian invader in reducing several Kshatriya chiefs of the Ashvakas of the Alishang/Kunar and Swat valleys. He appears to have done this in an understanding with Alexander that after the reduction of this territory, he would be made the lord of the country. And Arrian definitively confirms that after the reduction of the fort of Aornos in Swat where the Ashvakas had put up a terrible resistance, Alexander entrusted the command of this extremely strategic fort of Aornos to Shashigupta and made him the Satrap of the surrounding country of the eastern Ashvakas.

Towards the end of battle of Hydaspes (Jhelum), Arrian mentions a certain Meroes and attests him to be an Indian and an old friend of Porus (or Poros). Arrian further attests that he was finally chosen by Alexander to bring the fleeing Porus back for concluding peace treaty with Macedonian invader. It is notable that at the time of Porus's war with Alexander, Shashigupta, the satrap of the eastern Ashvakas had very cordial relations with Porus. In fact, he was on good terms both with Porus as well as Alexander and was finally chosen by Alexander to effect peace negotiations between him (Alexander) and Porus when Taxiles i.e. the ruler of Taxila had failed in this endeavour. It is more than likely, as several scholars have speculated, that Shashigupta may have alternatively been known also as Meroes (equivalent to the Sanskrit Maurya) after his native-land Meros (Mor or Mer in Prakrit, perhaps Mt Meru of Sanskrit texts). Another possibility is that name Meroes (Maurya?) may have been derived from "Mer" (hill or mountain) or "Mera" (hillman) as Sisicottos or Shashigupta was obviously a hilllman or mountaineer.^{[citation needed]}

A few months later when Alexander was still in Punjab and was engaged in war with the Glausais of Ravi/Chenab, the Ashvakas had assassinated Nicanor, the Greek governor of lower Kabul valley and also issued a threat to kill Shashigupta if he continued to cooperate with the invaders. While Phillipos was appointed to Nicanor's place, no further reference to Shashigupta by this name exists in classical sources. It appears likely that as a shrewd politician & statesman cum military general, Shashigupta had sensed the pulse of time and therefore, after deserting Alexander’ camp, he had thrown his lot with the emerging powerful group of insurgents. Thence afterward, Shashigupta seems to appear under an alternative name----Moeres or Moeris of the classical chroniclers. It is notable that Moeres, Moeris, Meris and Meroes are all equivalent terms. Arrian writes Meroes while Curtius spells it as Moeres or Moeris. Chieftain Moeris of lower Indus delta (Patala) referenced by Curtius seems precisely to be the same person as Meroes of north-west, attested to be old friend of Porus by Arrian. Alexander was apparently annoyed at this development and pursued Shashigupta who appears to have fled with his followers to lower Indus. He probably appears there as Moeres of Curtius, a chief of Patala. It is but natural that after joining the band of insurgents, Shashigupta alias Meroes or Moeres became a leader of the group of rebels and started his struggle for realizing his bigger goals for bigger regal power.^{[citation needed]}\

Sisikottos/Sisocostus appears twice in Arrian's Anabasis and once in Historiae Alexendri Magni by Curtius. Many scholars suggest that Shashigupta was a ruler of some frontier hill state south of Hindukush, it is however, more appropriate to call him a military adventurer or a corporation leader coming from the warlike background of the fierce Kshatriya clan of the Ashvakas from Massaga or Aornos (Pir-Sir) or some other adjacent territory of the Ashvakas. No ancient evidence is available which attests Shashigupta's royal background prior to his appointment by Alexander as ruler of the Ashvakas of the Aornos country.