Most people in India would have wondered atleast once or another as to why Bangalore became so much popular for IT. But careful observation reveals an interesting fact that except Delhi-NCR, no north Indian city any defence research and development center, including HAL, NAL, ISRO, DRDO, LRDE or PSUs like BEL, BHEL, BEML. These are all based almost in Southern India. It is said that because south India is surrounded in all 3 sides by water bodies, all these organizations are moved to south so that foreign infiltration would be less. There is a story that at one point of time, some of these organizations got some work outsourced to them from western countries. Thus More work came to Southern India followed by more talents and in turn more local companies started and foreign companies established their development centers! I don't know the authenticity of this story. May be somebody knowing anything on this might just give his opinion.