Going back to the history of Ayurveda, it was first described by Agnivesha in his book Agnivesha tantra. Later re written by Charaka and being named as Charaka Samhita, Sushruta Samhita was added to the former. These contained the text taken from the universities like Nalanda nad Takshashila.  Its conspicuous use of the word veda, or knowledge, reveals its role in early Hinduism and explains its popularity in India. The origin of Ayurvedic medical sciences is claimed to come from a divine revelation from Lord Brahma. Ayurveda was practiced during the time of Buddha (around 520 BC) , and in this period the Ayurvedic practitioners were commonly using Mercuric-sulphur combination based medicines.