The term Bon has been used to refer to several different phenomena. Drawing from Buddhist sources, early Western commentators on Bon used the term for the pre-Buddhist religious practices of Tibet. These include folk religious practices, cults surrounding royalty, and divination practices. However, scholars have debated whether the term Bon should be used for all of these practices, and what their relationship is to the modern Bon religion. In an influential article, R. A. Stein used the term the nameless religion to refer to folk religious practices, distinguishing them from Bon. Per Kvaerne uses Bon solely to refer to a tradition he dates from tenth and eleventh centuries CE, the tradition which developed into the modern Bon religion. Kvaerne identifies this tradition as an unorthodox form of Buddhism, but other scholars such as Samten G. Karmay take seriously Bonpo narratives which define Bon as a separate tradition with an origin in the land of 'Ol-mo lung-ring, part of Tazig, identified variously with Persia, Central Asia, or the area around Mount Kailash in the west of the Tibetan Plateau. The term Yungdrung Bon (Wylie: g.yung drung bon) is sometimes used to describe this tradition. Yungdrung refers to the left-facing swastika, a symbol which occupies in Bon a similar place as the vajra (Wylie: rdo rje) in Tibetan Buddhism, symbolizing indestructibility and eternity. Yungdrung Bon is a universal religion, although it is mainly limited to Tibetans, with some non-Tibetan converts.