Kerala traces its non-prehistoric cultural genesis to its membership (around the AD 3rd century) in a vaguely defined historical region known as "Thamizhagom" — a land defined by a common Tamil culture and encompassing the Chera, Chola, and Pandya kingdoms. At that time, the music, dance, language (first "Dravida Bhasha" — "Dravidian language" — then Tamil), and "Sangam" (a vast corpus of Tamil literature composed between 1,500–2,000 years ago) found in Kerala were all similar to that found in the rest of "Thamizhagom" (today's Tamil Nadu). The culture of Kerala evolved through the Sanskritization of Dravidian ethos, revivalism of religious movements and reform movements against caste discrimination. Kerala showcases a culture unique to itself developed through accommodation, acculturation and assimilation of various faculties of civilized lifestyle.