The rulers of the three Tamil dynasties were referred to as the "three crowned rulers (the mu-ventar) of the Tamil country". The age and the antiquity of the Pandya dynasty are difficult to establish. The early Pandya chieftains ruled their country (the Pandya nadu) from time immemorial, which included the inland city of Madurai and the southern port of Korkai. The Pandyas are celebrated in the earliest available Tamil poetry ("the Sangam literature"). Graeco-Roman accounts (as early as 4th century BCE), the edicts of Maurya emperor Asoka, coins with legends in Tamil-Brahmi script, and Tamil-Brahmi inscriptions suggest the continuity of the Pandya dynasty from the 3rd century BCE to the early centuries CE. The early historic Pandyas faded into obscurity upon the rise of the Kalabhra dynasty in south India.