Gajabahu synchronism
Gajabahu synchronism, also known as Gajabaju-Chenkuttuvan synchronism is a chronological tool used by scholars and historians to date early historic or pre-Pallava South India, especially the early Tamil history.
The method was first proposed by scholar V. Kanakasabhai Pillai in 1904 in his work "The Tamils Eighteen Hundred Years Ago" and was later supported by scholars such as K. A. Nilakanta Sastri. Historian Kamil Zvelebil, while acknowledging the fragility of this synchronism, famously called it the "sheet anchor" for dating early Tamil literature (the Sangam literature). It is based on the contemporaneity of the early historic Chera king Senguttuvan with Gajabahu I, the 2nd century CE Sri Lankan ruler. Complementary epigraphical/archeological evidence broadly seems to support the Gajabahu dating.