Nagarjuna and Charaka were patronised by which ruler?

Traditional historical accounts associate the Kushana emperor Kanishka with the patronage of Buddhist intellectuals including Ashvaghosha, Nagarjuna and the physician Charaka, though individual biographies contain legendary elements. This question belongs to the Gupta and post-Gupta phase, a period reconstructed through inscriptions, coins, monuments, literary works, scientific texts and accounts of foreign travellers. A reliable answer must connect the named ruler, author, work, institution, title or event with the correct chronology and source. The Gupta age is often described as a classical or golden age because of important achievements in Sanskrit literature, temple architecture, sculpture, astronomy and mathematics, but the label should not conceal regional diversity or social and political change.