Nāgārjuna [c. 150 – c. 250 CE (disputed)] was an Indian Mahāyāna Buddhist thinker, scholar-monk, philosopher, and the founder of the Middle Way School. He is widely considered one of the most important Buddhist philosophers. Jan Westerhoff considers him to be "one of the greatest thinkers in the history of Asian philosophy." Nāgārjuna is widely considered to be the founder of the Madhyamaka (centrism, middle-way) school of Buddhist philosophy and a defender of the Mahāyāna movement. His Mūlamadhyamakakārikā (Root Verses on Madhyamaka, or MMK) is the most important text on the Madhyamaka philosophy of emptiness. The MMK inspired a large number of commentaries in Sanskrit, Chinese, Tibetan, Korean and Japanese and continues to be studied today. India in the first and second centuries CE was politically divided into various states, including the Kushan Empire and the Satavahana Kingdom. At this point in Buddhist history, the Buddhist community was already divided into various Buddhist schools and had spread throughout India. At this time, there was already a small and nascent Mahāyāna movement. Mahāyāna ideas were held by a minority of Buddhists in India at the time. As Joseph Walser writes, "Mahāyāna before the fifth century was largely invisible and probably existed only as a minority and largely unrecognized movement within the fold of nikāya Buddhism." By the second century, early Mahāyāna Sūtras such as the Aṣṭasāhasrikā Prajñāpāramitā were already circulating among certain Mahāyāna circles. Very little is reliably known of the life of Nāgārjuna and modern historians do not agree on a specific date (1st to 3rd century CE) or place (multiple places in India suggested) for him. The earliest surviving accounts were written in Chinese and Tibetan centuries after his death and are mostly hagiographical accounts that are historically unverifiable. Some scholars such as Joseph Walser argue that Nāgārjuna was an advisor to a king of the Sātavāhana dynasty which ruled the Deccan Plateau in the second century.