The classical music tradition of the ancient and medieval Indian subcontinent (modern Bangladesh, India, Pakistan) were a generally integrated system through the 14th century, after which the socio-political turmoil of the Delhi Sultanate era isolated the north from the south. The music traditions of the North and South India were not considered distinct until about the 16th century, but after that the traditions acquired distinct forms.[2] North Indian classical music is called Hindustani, while the South Indian expression is called Carnatic (sometimes spelled as Karnatic). According to Nazir Ali Jairazbhoy, the North Indian tradition acquired its modern form after the 14th or the 15th century. See more