Gajabahu synchronism is the chronological device used by historians to help date early historic or pre-Pallava south India, esp.
[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.
[1] It is based on the contemporaneity of the early historic Chera king Senguttuvan and Sri Lankan ruler Gajabahu.
The 30th Canto, 160, in translation, reads - "The monarch of the world [Senguttuvan] circumambulated the shrine thrice and stood there proffering his respects.
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.