The scales of Behag are as follows :
Arohanam (Ascending) : S G3 M1 P N3 D2 N3 S’
Avarohanam (Descending) : S’ N3 D2 P M1 G3 M1 G3 R2 S
It is a Janya Raga, derived from Dhira Shankharabharanam, 29th on the Melakarta scale.
This raga is an import from Hindustani Music. Predominantly used for short tukkada pieces and light songs sung at the tail end of concerts, There a number of small compositions in this raga which I enjoy such as Muruganin Maru Peyar Azhagu by Guru Surajananda, Aadum Chidambaramo and Idu Dano Thillai Sthalam by Gopalakrishna Bharathi, Narayana Te Namo Namo by Annamacharya, Saramaina by Swati Thirunal. There is also a lovely Thillana by Lalgudi Jayaraman which I like very much.
Note : The 12 notes in the octave are named as below. Please note that C is used as Sa for the sake of simplicity as the scale is relative in Carnatic Music. Also note that the scales paint only a superficial picture of the raga as the gamakas(ornamentations) are a very important part of a raga.