The decline of Buddhism has been attributed to various factors. Regardless of the religious beliefs of their kings, states usually treated all the important sects relatively even-handedly. According to Hazra, Buddhism declined in part because of the rise of the Brahmins and their influence in socio-political process. According to some scholars such as Lars Fogelin, the decline of Buddhism may be related to economic reasons, wherein the Buddhist monasteries with large land grants focussed on non-material pursuits, self-isolation of the monasteries, loss in internal discipline in the sangha, and a failure to efficiently operate the land they owned. Monasteries and institutions such as Nalanda were abandoned by Buddhist monks around 1200 CE, who flee to escape the invading Muslim army, after which the site decayed over the Islamic rule in India that followed.