South India has historically been geographically inaccessible for foreign invaders. However, Muslims have tried to loot and plunder the region like the rest of India, but they have been largely unsuccessful.
Tipu Sultan, the Mughals, Malik Kafur, invaders from Hyderabad etc. have tried to conquer the South but were eventually repelled.
It's obvious that you have very little idea about the early medieval and later history of India ,old friend. Here let me be of some help to you.
You are right when you say that North was the first to face the Islamic incursions in the form of Arabic Invaders first and later Turkic invasions in Punjab and upper Ganga doab while South remained largely unmindful of all these events. There were several reasons behind that:
Firstly, Early Invaders were mostly raiders who had heard about the riches of Indo Gangetic valley and who didn't want to set up any permanent base in Hindustan. Thus they looted as much as they could and returned back to their homelands in Transoxiana and Khurasan. Prime example is Mahmud of Gahzna, an ambitious commander who between 999-1030 raided India multiple times (keep in mind when I say India here I include whole of the Punjab and KPK).
Secondly, even though Shahbuddin Gauri had ensured that Turks finally laid foundation of a permanent kingdom in Delhi, the early rulers of wrongly called 'slave dynasty' were wary of taking large expeditions in Hindustan on account of alien conditions, haughty Rajput resistance and the intra noble rivalry.
The last factor that is the factionalism among nobles as well as continous monhol incursions starting from the time of Iltutmish made sure that the Sultanate remained centred around Delhi and adjoining areas for the years to come even though a powerful Monarch like Balban ruled it in between these years.
The situation changed with the ascending of throne by Alauddin Khalji and here South India comes into the picture. Alauddin was an ambitious ruler who wasn't content with holding a mere fragment of land around Punjab. He embarked on an expedition to control most of the Hindustani mainland which took him beyond Vindhyas and eventually to the Southern India.
He first subjugated the powerful kingdom of Deogir in modern Maharashtra and later it's neighbor Warangal ruled by Kakatiyas. Later he ordered Malik Kafur, his favorite slave to raid lands till coromondal coast which he successfully did. Millions of people slaughterd, enslaved and converted (even though Alauddin wasn't big on the religion thing). Barani has written extensively about this quest gleefully describing the killings.
Except Hoysalas(who ruled area around modern Karnataka) almost whole South was taken under control of Khaljis.
And after downfall of Khalji empire , new Sultanates in Madurai and later near Krishna Tungbhadra doab which came to be known as Bahamani Sultanate were founded.
Thus South remained in the Muslim possession for around 200 years before the arrival of Mughals. Bahamani Sultanate got broken into 5 different individual Muslim empires who were later subjugated by Aurangzeb in his famous Deccan campaign.
Therefore your assessment about South chillaxing while North remained in turmoil is completely baseless since we have seen that Muslim dynasties started springing up in South as early as 13th century .
. At least once in your life, try reading outside Bhakt websites and fake news.
