There are two sets of classic texts , all written originally in Samskrit, now translated in many contemporary languages including English.
They are : Brihattrayee – 1 Charaka Samhita 2 Sushruta Samhita 3 Samhitas of Vagbhatta (Astaanga Hridayam and Astaanga Sangraha) Authors of the above texts are Agnivesha /Charaka , Sushruta /Nagarjuna & Vagbhatta 1st & 2nd respectively Historicity of the above texts is 700 BC , 600 BC and 300 AD respectively. The subject of Charaka Samhita is Medicine & Philosophy and the theme of Sushruta Samhita & Samhitas of Vagbhatta are Surgery-Anatomy & Therapeutics respectively.
Like Brihatrayee there are also three texts in this second group. 1 Madhava Nidaana : It has been witten by Maadhavakara . The time of it is 900 AD . Diagnostics is the main theme. 2 Shaarangadhara Samhita which is written by Shaarangadhar in 1300 AD . The subject of this text is Therapeutics. 3 Bhasva Prakaasha which is taken down by Bhaava Mishra in 1600 AD . The subject of this text is Drugs and Meteria Medica.
In Samhitas Ayurveda has been divided into eight parts