Gajabahu synchronism is the chronological device used by historians to help date early Tamil history.[1] The synchronism, first propounded by V. Kanakasabhai Pillai in 1904 in his The Tamils Eighteen Hundred Years ago, was adopted by some scholars of the time to date Tamil literature. Kamil Zvelebil, even while acknowledging the fragility of the synchronism, called it the "sheet anchor" of the dating of Tamil literature.