quality:corruption, linguistic:paraphrasing, structural:expansion, information:filtering, linguistic:voice_change
Period of reign

The Mathura pillar inscription of Chandragupta II (as well as some other Gupta inscriptions) mention two dates: several historians have assumed that one of these dates denotes the king's regnal year, while the other date denotes the year of the Gupta calendar era. However, Indologist Harry Falk in 2004 has theorised that the date understood to be the regnal year by the earlier scholars is actually a date of the kālānuvarttamāna system. According to Falk, the kālānuvarttamāna system is a continuation of the Kushana calendar era established by emperor Kanishka, whose coronation Falk dates to 127 CE. The Kushana era restarts counting after a hundred years (e.g. the year after 100 is 1, not 101).

The date portion of the Mathura inscription reads (in IAST):

The letters before the words kālānuvarttamāna-saṃvatsare are abraded in the inscription, but historian D. R. Bhandarkar (1931–1932) reconstructed them as gupta, and translated the term gupta-kālānuvarttamāna-saṃvatsare as "year following the Gupta era". He translated the entire sentence as:

Historian D. C. Sircar (1942) restored the missing letters as "cāme" ("fifth") and concluded that the inscription was dated to the Chandragupta's fifth regnal year. The missing letters have alternatively been read as "prathame" ("first"). According to these interpretations, the inscription is thus dated in year 61 of the Gupta era, and either the first or the fifth regnal year of Chandragupta. Assuming that the Gupta era starts around 319–320 CE, the beginning of Chandragupta's reign can be dated to either 376–377 CE or 380–381 CE.

Falk agrees that the missing letters denote a numerical year, but dismisses Sircar's reading as "mere imagination", pointing out that the missing letters are "abraded beyond recovery". In support of his Kushana era theory, Falk presents four Gupta inscriptions (in chronological order) that mention the term kālānuvarttamāna-saṃvatsare:

Falk notes that the "dynastic year" in the table above appears to be a year of the Gupta era. The kālānuvarttamāna year cannot be regnal year, because Chandragupta I is not known to have ruled for as long as 61 years. If we assume "61" of the Mathura pillar inscription denotes a year of the Gupta era (as assumed by Bhandarkar, Sircar and other scholars), we must assume that "15" of the Buddhist image pedestal also denotes a year of the Gupta era: this is obviously incorrect, since Kumaragupta I ruled after Chandragupta II. Scholars K.K. Thaplyal and R.C. Sharma, who studied the Buddhist image pedestal inscription, speculated that the scribe had mistakenly interchanged the years 121 and 15, but Falk calls this assumption unnecessary.

According to Falk, the discrepancy can be explained satisfactorily, if we assume that the kālānuvarttamāna era denotes a system that restarts counting after a hundred years. The Yaksha figure inscription is dated to year 112 of the Gupta era (c. 432 CE), which corresponds to the kālānuvarttamāna year 5. Thus, the kālānuvarttamāna era used during Kumaragupta's time must have started in 432–5 = 427 CE. The years mentioned in the Buddhist image pedestal inscription also suggests that the epoch of this era was c. 426–427 CE. Since the kālānuvarttamāna system restarts counting every 100 years, the kālānuvarttamāna era used during the reign of Chandragupta II must have started in 327 CE. Thus, the Mathura inscription can be dated to 327+61 = c. 388 CE. While Falk's theory does not change the Gupta chronology significantly, it implies that the date of the Mathura inscription cannot be used to determine the beginning of Chandragupta's reign.

The Sanchi inscription, dated to 412–413 CE (year 93 of the Gupta era), is the last known dated inscription of Chandragupta. His son Kumaragupta was on the throne by the 415–416 CE (year 96 of the Gupta era), so Chandragupta's reign must have ended sometime during 412–415 CE.