The Asampurna Melakarta (transliterated as Asaṃpūrṇa Mēḷakarta) scheme is the system of 72 ragas (musical scales) originally proposed in the 17th century by Venkatamakhin in his Chaturdanda Prakasikha.
[1][2] Some ragas though are the same in both systems (like 15 - Mayamalavagowla and 29 - Dheerasankarabharanam), and in some cases the scales are same, while names are different (like 8 - Janatodi and Hanumatodi, 56 - Chamaram and Shanmukhapriya).
Later Venkatamakhin expounded in the 17th century in his work Caturdandi Prakaasikaa a new mela system known today as melakarta.
[1] He had made some bold and controversial claims and defined somewhat arbitrarily 6 swaras from the known 12 semitones, at that time, to arrive at 72 melakarta ragas.
The controversial parts relate to double counting of R2 (and similar swaras) and his exclusive selection of madyamas for which there is no specific reasoning (also known as asampurna melas as opposed to sampurna ragas).