freinds, after the advent of vijaynagar empire the west coast lost its independence. there were some corrupt local regimes. the arabs were at the peak of their power in west asia and the coast line from karwar to cape comorin their influence was unchecked. the come during the eastward winds stay for a few month marry a local woman and leave by the westward winds start. before they leave without forgetting to say thalak". the mapilla style invasion is evident all over from kasarkod to kozhikode. their population increased to almost a majority by another century.
the portugese arrived in 1490s and they too estabilished a monopoly in the strech between kozhicode to kollam. the genetic mixture was much more severe and almost 50% of the population in kerala is european or arab descendent.
the population in kerala is thus neither aryan,dravidian or aborigine but a mixed mulattoe. an average keralite thinks their father land is elsewhere even as they think their motherland is westcoast. the fact keralite go anywhere to work is due to this foreign seafarer gene influence.
kerala stabilised only after tippu's fall when it was annexed into madras province. the travancore state got estabilished slightly befor that and could prove stability almost for 2 centuries.
no doubt kerala was a tamil sphere till 12-13 century. but after that things went into a very very nasty turn which keral does not want to write it in paper.