Pann

Pann () is the melodic mode used by the Tamil people in their music since the ancient times. The ancient "panns" over centuries evolved first into a pentatonic scale and later into the seven note Carnatic Sargam. But from the earliest times, Tamil Music is heptatonic and known as Ezhisai (ஏழிசை).
"Panns" in literature.
There are several references to music and "Panns" in the ancient pre-Sangam and Sangam literature starting from the earliest known work Tholkappiyam (500 BCE). Among Sangam literature, "Mathuraikkanci" refers to women singing "sevvazhi pann" to invoke the mercy of God during childbirth. In "Tolkappiyam", the five landscapes of the Sangam literature had each an associated "Pann", each describing the mood of the song associated with that landscape. Among the numerous "panns" that find mention in the ancient Tamil literature are, "Ambal Pann", which is suitable to be played on the flute, "sevvazhi pann" on the "Yazh" (lute), "Nottiram" and "Sevvazhi" expressing pathos, the captivating "Kurinji pann" and the invigorating "Murudappann".
The Sangam landscape was classified into five regions to describe the mood of the poem and to describe the intangibles of human emotions. While describing life and romance, the poets employed the background of the natural landscape and used the "pann" specific to that landscape to provide the mood. The "neithal" (seaside) landscape, which is employed to convey the grief of separation of lovers had the associated "sevvazhi pann" expressing pathos. "Malaipatukatam" mentions Viraliyar singing "Kurinjipann" when offering worship to the deities of the mountainous regions. It also refers to Virali singing "Marudappann" before singing the eulogies of kings. Malaippadukadam also refers to the people trying to overcome their fatigue by singing "Marudappann" after working in the fields. There is a very interesting reference to Panns and birds/insects in "Perumpanarruppatai". It says that the beetles liked to listen to "Kurinjipann" played on Vilyazh thinking it to be the voice of its own kith and kin, while they hated to listen to "Palaipann" played on flute. There are also references to the Panar taking delight in mastering the "Naivalam pann".
Evolution of "Panns".
The post-Sangam period, between the third and the fifth centuries CE, Tamil music evolved to a higher sophistication. Silappatikaram, written around the fifth century CE, describes music based on logical, systematic and scientific calculations in the arrangements of the dancers on the stage to represent the notes and "panns". "silappatikaram" contains several chapters dedicated to music and dance, of which the most famous is the "kanal vari" which is a duet between the hero Kovalan and his lady-love Madavi. "Cilappatikaram" contains musical terminology such as, "azhaku" and "matthirai" referring to the musical pitch and the smallest fraction of an audible sound distinguishable by the human ear. From these evolved the scales. 
Development of scales.
One of the first scales employed by the ancient Tamils was the "Mullaippann", a pentatonic scale composed of the notes "sa ri ga pa da" equivalent to C, D, E, G and A in the western notations. These fully harmonic scales, constitutes the "raga" "Mohanam" in the Carnatic music style.
"Mullaippann" further evolved into "Sempaalai", a scale based on seven notes by the addition of two more notes, "ma" and "ni" to the pentatonic scale. "Sempaalai pann" corresponds to the Carnatic raga Harikambhoji. In ancient Tamil, the seven notes were termed as "kural", "tuttam", "kaikkilai", "uzhai", "ili", "vilari" and "taaram". The seven basic notes are then developed into twelve swaras corresponding to the twelve houses of the zodiac. 
The ancient Tamils also derived new "panns" by the process of modal shift of tonic and by the process of reallocating the pitch and beat of the notes. "Cilappatikaram" has an example of this in the chapter "Arangetrukadai", where the "Pann Mercharupalai" is changed to derive a new "Pann". By the model shift of the tonic (பண்ணுப்பெயர்த்தல்) the ancient Tamils devised the seven major "palais". Using the process of the cycle of fifth (called "aaya palai") or the cycle of fourth, five semitones were developed. For example, if the cycle is started with "kural" ("sa"), the fifth note will yield "iLi" ("pa"), the "sa"-"pa" relationship. In the cycle of fourth, "kural" ("sa") will give "uzhai" ("ma"), the "sa"-"ma" relationship. These five semitones were added to the original seven notes giving 12 notes of the ancient Tamil musical octave. Among the 12 notes, the flats were called "kuRai" (குறை) and the sharps were called "nirai" (நிறை).
The seven major "palais" or parent scales of the music of the ancient Tamils are: "Sempalai" (corresponding to the present "Harikambhoji"), "Padumalai Palai" ("Natabhairavi"), "Sevvazhi Palai" ("Hanumatodi"), "Arum Palai" ("Dheerasankarabharanam"), "Kodi Palai" ("Kharaharapriya"), "Vilari Palai" ("Hanumatodi"), and "Merchem Palai" ("Mechakalyani"). 
The four original "panns" of "maruthappann", "kurinchippann", "sevvazhi" and "sadari" thus evolved into 103 "panns" with varying characterisations. In all of these PaNs, Uyir SurangaL (Jeevaswarams: Life Notes) exist. The life note of a PaN is embellished according to the notes that appear immediately before and after. This is called Alangaaram (Gamakkam). Taking into consideration all these special notes, PaN Isai is different from Karnatik Music. Karnatik Music as two variations of each of the variables; Ri, Ga, Ma, Dha and Ni. PaN Isai has 4 variations of each of the 5 variable. Plus the 2 constants; Sa and Pa, there are 22 variations of the 7 basic notes.The ancient name for Raagam is Niram. Melakarta was called Thaai Niram and Raagams born from there were call Say Niram. The ancient name for ThaaLam is PaaNi. For example, Rupaka Talam was PaaNi MoonDRoththu. Before Sa, Ri, Ga... Tamils used the 12 Tamil Vowels. Looking at a keyboard, they would've used the 5 KuRil (Short Sounds) for the black keys and the 7 NeDil (Long Sounds) for the white keys.
Some of the "panns" and their equivalent Carnatic ragas were:
"Panns" in Saivite hymns.
After the Sangam period and during the occupation of the Tamil country by Kalabhras, Tamil music was dormant for a period of a few centuries. With the advent of the Saivite saints Manikkavacakar (100 AD), Sundarar (900 AD), Thirunavukkarasar and Thirugnana Sambanthar (7th century CE) who used the ancient "panns" in their hymns (Tevaram), Tamil music experienced a revival. Only through these Tirumurais, hymns by Seerkaazhi Muthuthaandavar, hymn by Marimutha Pillai, Arunagirinathar, Ramalinga Swamigal and the hymns of Vaishnavite Alvars we can still experience the ancient traditions of the Tamil "panns". Sambanthar used the following seven "panns": "nattapaadai", "Thakka ragam", "Pazhanthakka ragam", "Thakkesi", "Kurinji", "Viyazhak kurinji", and "Meharahakkurinji". Manikkavacagar used Mulai Pann (Mohana Raagam) for the majority of his Thiruvasagam and Thirukkovaiyar. There are a few of his hymns where he used Bowli, Megaragakkurinji and Kalyaani. Sundaramoorthi SwamigaL wise widely influenced by Thirunyaanasambandhar SwamigaL and Thirunaavukkarasar 'Appar' SwamigaL, who used PaN Koli quite often. In actual, only Thirunaavukkarasar SwamigaL sang the Dhehvaaram, which made-up the 4th, 5th and 6th ThirumuRaigaL. Thirunyaanasambandhar SwamigaL wrote the ThirukaDaikaapu, which makes up the 1st, 2nd and 3rd ThirumuRaigaL. Thiru Sundharamoorthi SwamigaL wrote the ThirupaaTTu, which makes up the 7th ThirumuRai. Thiru MaaNikkavaasagar's Thiruvaasagam and Thirukkohvaiyaar makes up the 8th ThirumuRai. There 12 ThirumuRais. Thirumoolar's Thirumandhiram is the 10th ThirumuRai and SekkiZHaar's Thiru ThoNDar PuraaNam, or Periya PuraaNam is the 12th ThirumuRai. The ThirumuRais are the Devotional works of Saivaism and the 14 SaathirangaL (Saathirais) are the philosophical works of Saivaism, with ThiruvaLuvar's ThirkkuRaL accepted as Neethi nool or Saathiram (Singular form of SaathirangaL).