What is with this North and South.Divide?

Everytime i visit a new country, I ask people … how common are people across the country? most people tell me that the country is quite similar when compared west to east however when compared north to south cultures are quite different…attitude are quite different. Evidently there are more North and south divide of countries rather than east and west! There is North Korea/South Korea. There is North Sudan/South Sudan. However I don’t recollect many East/west of course needless to say, Germany couldn’t stay separated for for long politically and by heart, they were never separated.   

Ask an Indian, what is difference between South Indian and North Indian…everyone has a strong opinion! Ask a chinese, reaction is similar! Ask an American, most may not know that there are states other than theirs but the knowers firmly believe that the north east coast is very different from south and south west coast! UK no different but London is too different anyways isn’t it!