Zhangzhung or Shangshung was an ancient culture and kingdom of western and northwestern Tibet, which pre-dates the culture of Tibetan Buddhism in Tibet. Zhangzhung culture is associated with the Bon religion, which in turn, has influenced the philosophies and practices of Tibetan Buddhism. Zhangzhung people are mentioned frequently in ancient Tibetan texts as the original rulers of central and western Tibet. Only in the last two decades have archaeologists been given access to do archaeological work in the areas once ruled by the Zhangzhung.

Recently, a tentative match has been proposed between the Zhangzhung and an Iron Age culture now being uncovered on the Changtang plateau in northwestern Tibet.

According to Annals of Lake Manasarowar (Lake Manasarovar), at one point the Zhang Zhung civilization consisted of 18 kingdoms in the west and northwest portion of Tibet. The Zhang Zhung culture was centered on sacred Mount Kailash and extended west to Scythia and present-day Ladakh & Baltistan, southwest to Jalandhar, south to the Kingdom of Mustang in Nepal, east to include central Tibet, and north across the vast Chang Tang plateau and the Taklamakan Desert to Shanshan. Thus the Zhang Zhung culture controlled the major portion of the "roof of the world".

Tradition has it that Zhang Zhung consisted "of three different regions: sGob-ba, the outer; Phug-pa, the inner; and Bar-ba, the middle. The outer is what we might call Western Tibet, from Gilgit in the west to Dangs-ra khyung-rdzong in the east, next to lake gNam-mtsho, and from Khotan in the north to Chu-mig brgyad-cu rtsa-gnyis in the south. The inner region is said to be sTag-gzig (Tazig) [often identified with Bactria], and the middle rGya-mkhar bar-chod, a place not yet identified." While it is not certain whether Zhang Zhung was really so large, it is known that it was an independent kingdom and covered the whole of Western Tibet.

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