You "North Indians" have been raped more than anybody else in India because you are sitting right at the exit of the Khyber pass and so got raped by every race of invaders that entered India that way: the Persians, the Greeks, the Sakas, the Hephtalites, the Turks, the Afghanis, etc. That is why you have such white skin. All the said invaders had white skin.
However, there is no evidence that the South of India was ever conquered by the North. Brahminism and Buddhism certainly spread from north to south but it does not appear to have been accompanied by conquest. Some parts of the south were at various times vassals of northern Empires (Maurya, then Gupta), but there is no evidence of massive military operations by said Empires into the south. By the Way, according to your definition, neither the Mauryas nor the Guptas were "North Indians", but were "Gangetics" instead. Both originated in Bihar (Magadha at the time) and had their capital in Patna (then called Pataliputra).
English is indeed an Aryan language but, above all, it is a useful language. In India, every valuable activity is conducted in English, while Hindi is only used for bullshit: politics and Bollywood.