The Buddhist saint Nagarjuna, who lived in South India in approximately the second century CE, is undoubtedly the most important, influential, and widely studied Mahayana Buddhist philosopher. His many works include texts addressed to lay audiences, letters of advice to kings, and a set of penetrating metaphysical and epistemological treatises. His greatest philosophical work, the Mulamadhyamikakarika—read and studied by philosophers in all major Buddhist schools of Tibet, China, Japan, and Korea—is one of the most influential works in the history of Indian philosophy.