Bon, also spelled Bön, is a religion of Tibet. The modern form of Bon has its roots in the late 900s and 1000s CE, when the first Bon monasteries were started in Tibet. There are many teachings in Bon that are similar to Buddhist teachings, and so people who study Bon disagree whether it should be called a kind of Buddhism or not. Followers of Bon believe that it was founded by a teacher called Tonpa Shenrab who lived many years ago in a land called Tazig. Some people think that Tazig refers to Persia, Central Asia, or the area around Mount Kailash in western Tibet. According to Tibetans, Bon was popular in Tibet before Buddhism became the main religion of Tibet, but some non-Tibetans like Per Kvœrne say there isn't much connection between religion in Tibet before Buddhism and the living tradition of Bon. After the Chinese army sent troops to Tibet in 1959, some followers of Bon were forced to leave Tibet and many Bon monasteries and temples were shut down. Many of the followers of Bon who left Tibet started Bon centers in cities around the world. Today, most people who believe in Bon are ethnic Tibetans, but a small number of non-Tibetans have started to believe in Bon too. 