wiki/History_of_South_India#Prehistory
The history of southern India covers a span of over four thousand years, during which the region saw the rise and fall of a number of dynasties and empires.
The period of known history of southern India begins with the Iron Age (c. 1200 BCE – 200 BCE), Sangam period (c. 600 BCE – 300 CE) and Medieval southern India until the 15th century CE. Dynasties of Chera, Chola, Pandyan, Pallava, Travancore, Cochin, Zamorin, Kolathunadu, Chalukya, Satavahana, Rashtrakuta, Western Ganga, Kakatiya, Hoysala, Seuna, Bhonsle, Gaekwad, Scindia, Holkar, Patwardhan, Sangama, Saluva, Tuluva, Aravidu and Bahmani were at their peak during various periods of history.
History Palakkad gap
Chera Nadu and Kongu Naduwere territorial divisions in the ancient Tamilakam, which were separated by the Western Ghats.[1] An ancient highway called Rajakesari Peruvazhiconnected the regions via the Palakkad Gap, and was part of an extended trade that extended from Muziris in the western coast to Arikamedu on the eastern coast of the Indian subcontinent.[1][2] The local chieftains of the Kongu region made marriage alliances with the Cheras, which resulted in a migration of significant population between the regions via the Palakkad Gap.[1][3] Between first and fourth centuries CE, the Chera country consisted of most of the present day Kerala and western Tamil Nadu, and the gap enabled them to rule the territory from their capital at Karuvur[4] The Tamil Brahminsmigrated to Palakkad from central Tamil Nadu via the gap between the 15th to 18th centuries CE
Rajakesari Peruvazhi (lit. 'Highway of the Lion King[a]') was an early historic and medieval highway that traversed the present-day states of Tamil Nadu and Kerala in southern India. In the historic Tamilakam (the Tamil country), the highway connected the regions of western Chera Nadu(Kerala) and Kongu Nadu (western Tamil Nadu), which were separated by the Western Ghats. The highway passed through the Palghat Gap in the Western Ghats[5] and also through Perur, Vellalur, and Sulur.[6] It formed part of a route linking the port of Muchiri (Muziris) in the western coast(the Malabar Coast) of southern India with Arikamedu on the eastern coast, and was part of an extended trade network connecting the Mediterranean/Middle East and Southeast Asia/East Asia