According to  Bhatkhande- all the countless number of  North Indian Ragas are descendants of these ten Scales called Thaats.  These are: 1. Bilaaval. 2. Khamaaj. 3. Kaafi. 4.  Asaawari. 5. Bhairaav. 6. Bhairavi. 7. Kalyaan. 8. Maarwa. 9. Purvi. 10. Todi.  This tape gives the outline of the Thaats and an example of a song in the corresponding Ragas.  Both the outlines and songs are in Tala.  This is not only for musicians!! It is for all who need to widen the range of the hearing frequencies- which means everybody!