Gajabahu synchronism is the chronological device used by historians to help date early historic or pre-Pallava south India, esp. early Tamil history.[1][2] The method was famously supported by scholar K. A. Nilakanta Sastri.[2] Historian Kamil Zvelebil, even while acknowledging the fragility of the synchronism, famously called it the "sheet anchor" of the dating of early Tamil literature.
In the Tami epic Silappatikaram, there is reference to a certain "Kayavaku", the king of Sri Lanka. He is said to have attended the coronation of the Chera king Senguttuvan.
The 30th Canto, 160, in translation, reads -
"The monarch of the world [Senguttuvan] circumambulated the shrine thrice and stood there proffering his respects. In front of him the Arya kings released from prison, kings removed from central jail, the Kongu ruler of Kudagu, the king of Malva and Kayavaku, the king of sea-girt Ceylon, prayed reverently to the deity thus...[3]
Kayavaku here, despite some disagreement has been conjectured to mean Gajabahu, the ruler of Sri Lanka.[5] The Silappatikaram, therefore is read to imply that, Gajabahu was a contemporary of the Chera king Senguttuvan, the protagonist of the epic. Sri Lankan history, however records the reign of two Gajabahus. According to the Mahavamsa, the historical chronology of Sri Lanka, Gajabahu I reigned between 113—134 CE, while Gajabahu II reigned in the 12th century CE.
Kanakasabhai Pillai's reasoning for not considering Gajabahu II as the king mentioned in Silappatikaram is as follows:
In the long list of kings of Sri Lanka preserved in Singhalese chronicles, the name Gajabahu occurs only twice. Gajabahu I lived in the early part of the second century AD and Gajabahu II in the twelfth century. If the latter was king referred to in the Cilappathikaram, Karikala Chola, the grandfather of the Gajabahu contemporary, Imaya Varamban should have lived in the eleventh or twelfth century AD. But in many Tamil poems and inscriptions on copper plates recording the grants of Chola kings who lived in the tenth and the eleventh centuries, Karikala Chola I is described as one of the earliest and most remote ancestors of the Chola kings then reigning. It is evident therefore that the Gajabahu referred to in the Cilappathikaram could not be Gajabahu II, but must have been Gajabahu I, who was king of Ceylon from about AD 113 to AD 125.[6]
This, in turn, has been used to imply that the Chera king Senguttuvan, who, according to the Pathirruppatthu Collection ruled for 55 years may be dated to c. 110—165 CE.[7]
Kanakasabhai Pillai also mentions another reference from Silappatikaram which has the Chera king meet the Magadha king Nurruvan Kannar who is interpreted to as Satakarni, which was a common among the Satavahana and Andhra dynasties as an additional proof for the synchronism.[8]
Scholar Herman Tieken criticizes this synchronism as of circular logic.[9]
^Pillai, Vaiyapuri (1956). History of Tamil Language and Literature; Beginning to 1000 AD. Madras, India: New Century Book House. p. 22. We may be reasonably certain that chronological conclusion reached above is historically sound
^P. T. S. Iyengar in his "History of the Tamils"(p335) advances the theory that Kayavaku ought to be read as Kaval