According to Vishnu Narayan Bhatkhande (1860-1936), one of the most influential musicologists in the field of North Indian classical music in the twentieth century, each one of the several traditional ragas is based on, or is a variation of, ten basic thaats, or musical scales or frameworks. The ten thaats are Bilawal, Kalyan, Khamaj, Bhairav, Poorvi, Marwa, Kafi, Asavari, Bhairavi and Todi; if one were to pick a raga at random, it should be possible to find that it is based on one or the other of these thaats. For instance, the ragas Shri and Puriya Dhanashri are based on the Poorvi thaat, Malkauns on the Bhairavi, and Darbari Kanada on the Asvari thaat. It is important to point out that Bhatkande’s thaat-raga theory is not very accurate, but it is nevertheless an important classificatory device with which to order, and make sense of, a bewildering array of ragas; and it is also a useful tool in the dissemination of the music to students.
There are certain rules for these Thaats.
⦁ A Thaat must have seven notes out of the twelve notes [Seven Shuddha, Four komal (Re, Ga, Dha , Ni), one teevra (Ma) ], placed in an ascending order. Both the forms of the notes can be used.
⦁ Thaat has only an Aaroha.
⦁ Thaats are not sung but the raags produced from the Thaats are sung.
⦁ Thaats are named after the popular raag of that Thaat. For example Bhairavi is a popular raag and the thaat of the raag Bhairavi is named after the raag.
The 10 basic thaats acording to the Bhatkhande System are as follows
Bilawal is the most basic of all the ten thaats. All the swars in the thaat are shuddha or all swars in the natural scale. Bilawal as a raag is not rendered these days however a small variation of the raag called Alahaiya Bilawal is very common. This is a mornig raag and its pictorial descriptions create a rich, sensuous ambience in consonance with its performance.
Raags in Bilawal Thaat : Deskar, Haunsdhwani, Variations of Bilawal.
The next thaat is Khamaj which can be obtained by replacing the Shuddha Nishad of Bilawal by Komal Nishad. The raags of this thaat are full of Shringar Ras (romantic) hence this raag is mostly rendered in the form of light classical thumris, tappas, horis, kajris etc. Its pictorial descriptions in the existing texts are sensuous and even today, the raag Khamaj is considered to be a ‘flirtatious’ raag. There is another theory which assumes that in the past, Khamaj scale found its way in Ch’in music of the late medieval China.
Raags in Khamaj Thaat : Rageshree, Jhinjhoti, Des, Tilak Kamod, Jaijaiwanti, Khambavati etc.
Kafi thaat makes use of the Komal Gandhar and Komal Nishad. So basically it adds Komal Gandhar to the Khamaj Thaat. raag Kafi is one of the oldest raags and its intervals are described as basic scale of the Natyashastra. Thus in ancient and medieval times, Kafi was considered as natural scale. Kafi is a late evening raag and said to convey the mood of spring time.
Raags in Kafi Thaat : Dhanashree, Dhani, Bhimpalasi, Pilu, Megh Malhar, Bageshree etc.
Add Komal Dhaivat to Kafi thaat and you get Asavari Thaat. raag Asavari is full of tyag, the mood of renunciation and sacrifice as well as pathos. It is best suited for late morning. However important evening/night raags like Darbari and Adana also use notes of asavari thaat with different styles, stress points and ornamentations.
Raags in Asavari Thaat : Asavari, Desi, Darbari, Adana, Jaunpuri etc.
Bhairavi makes use of all the komal swars, Rishabh, Gandhar, Dhaivat, Nishad. When singing compositions in Bhairavi raag, the singers however take liberty to use all the 12 swars. Bhairavi raag is names after the shakti or feminine aspect of the cosmic life force, which is personified as a consort to Lord Shiva. Bhairavi is a powerful raag filled with devotion and compassion. Bhairavi is actually performed early in the morning in a peaceful, serious and ocassionally sad mood. Traditionally it is rendered as the last item of a program, for its unique fullness of sentiments as well as its wide scope of the tonal combinations. Pictorially, Bhairavi is represented in female form, as the wife of Bhairav.
Raags in Bhairavi Thaat : Malkauns, Bilaskhani Todi, Bhupali Todi, Kaunsi Kanada etc.
Bhairav thaat raags make use of Komal Rishabh and Komal Dhaivat. Bhairav is one of the names of Lord Shiva especially in his powerful form as a naked ascetic with matted locks and body smeared with ashes. The raag too has some of these masculine and scetic attributes in its form and compositions. The raag itself is extremely vast and allows a huge number of note combinations and a great range of emotional qualities from valor to peace. You can see a lot of variations on raag Bhairav including (but not restricted to) Ahir Bhairav, Alam Bhairav, Anand Bhairav, Bairagi Bhairav, Beehad Bhairav, Bhavmat Bhairav, Devata Bhairav, Gauri Bhairav, Nat Bhairav, Shivmat Bhairav. This raag is usually performed in a devotional mood in the early morning hours. The vibrations of the notes in Bhairav is said to clear one’s whole mind. The pictorial depictions of raag Bhairav in the ancient texts are austere as well as awe-inspiring.
Raags in Bhairav Thaat : Ramkali, Gunkari, Meghranjani, Jogiya, Bhairav and its variations etc.
Kalyan thaat consists of a important group of evening raags. Characterized by the teevra Madhyam, this thaat literally means good luck. It is considered to be a blessing-seeking and soothing raag. As a result, it is performed in the evening at the beginning of a concert. This raag creates a feeling of the unfolding of an evening. This thaat is huge and consists of many variations on the basic kalyan thaat including raags (but not restricted to) like Shuddha Kalyan, Shyam Kalyan, Yaman Kalyan, Anandi Kalyan, Khem Kalyan (Haunsdhwani + Yaman), Savani Kalyan etc.
Raags in Kalyan Thaat : Yaman, Bhupali, Hindol, Kedar, Kamod, etc.
Marwa thaat is obtained by adding a komal Rishabh to Kalyan thaat. The mood of the Marwa family raags is strongly and easily recognizable. The Shadja remains in the form of a shadow till the very end, where it almost comes as a surprise. komal Rishabh and shuddha Dhaivat are ver important. The overall mood of this raag is of sunset where the night approaches much faster than in northern latitudes. The onrushing darkness awakens in many observers, a feeling of anxiety and solemn expectation.
Raags in Marwa Thaat : Marwa, Puriya, Bhatiyaar, Bibhas, Sohoni etc.
Poorvi thaat adds a komal Dhaivat to Marwa thaat. These thaat raags usually feature komal Rishabh, shuddha Gandhar and Shuddha Nishad along with teevra Madhyam, the note which distinguishes evening from the morning raags (dawn and sunset). The thaat raag Poorvi is deeply serious quite and mysterious in character and is performed at the time of sunset. Pictorial depictions in early texts, often mention the poise, grace and charm of Poorvi.
Raags in Poorvi Thaat : Puriya Dhanashree, Gauri, Shree, Paraj, Basant etc.
Todi is the king of all thaats. Todi pictures nearly always show a petite, beautiful woman, holding veena, with a deer around her, standing in a lovely, lush green forest. Todi represents the mood of delighted adoration with a gentle, loving sentiment and its traditionally performed in the late morning.
Raags in Todi Thaat : Miyan Ki Todi, Gujari Todi, Madhuvanti, Multani etc.