Partly because there is a conscious decision to stick to its roots, and Vedic ideals, the south still has a soul and one can actually feel a palpable difference between the south and the north. Incidentally, a recent study has established that even monkeys from the south are more cultured and civilized than those from the north ! The energy levels are different and this important difference can be felt almost immediately after crossing the Vindhyas. Amongst other positives , it is very obvious that people in the south have a much stronger value system than those in the north. Besides, southerners are generally gentler, more caring, more at peace, less corrupt and yet remarkably open to favourable new influences and trends. In fact, they seem to possess a very good radar system which allows them to assimilate the best from changes rapid or otherwise -- taking place both locally and globally and thus stay in the forefront of knowledge frontiers while rejecting systems or short term value ideas that could develop into a threat to the continuity you mention. And on this count and other counts, successive invasions and foreign domination or elements alone cannot be held responsible for the erosion and corrosion that has taken place and is continuing in the north, but thats another subject.
