Introduction

The geographical extent of what constitutes “Tibet” (Bod/ Bautai/ Baitai/ Tubbat/ Fa/ Tufan) in this contribution varies considerably as the Tibetan empire (ca. 600– 850 CE) expanded and contracted at its various borders over time. In fact, even the existence of the very thing at the beginning of the seventh century is open to debate, and so I shall prefer to speak of the empire of the Yar lung (/ klung) dynasty. This indicates the hereditary lineage of power originating in and based around the Yar lung valley, in what I shall call for ease “central Tibet,” corresponding to the more eastern part of the area marked “Bod” (the standard Tibetan word for Tibet) on Map 8. From this power base, the Yar lung dynasty expanded in all directions except much to the direct south (due in part to the Himalayas), and so the land that Arabic sources of this period, for instance, called Tubbat was situated west of China, north of India, south of the Uyghur Turkic territories, and east of the Khurasan marches.

The Yar lung dynasty's power base was at first ensured by alliances with a small collection of other minimally developed nomadic-pastoralist and agricultural families or clans centred around the relatively fertile region through which the gTsang po River (or Brahmāputra) flows. The increase in their power meant coming to rule over a far larger but still sparsely populated area, corresponding to the Tibetan Plateau and even beyond, inhabited by connected ethnic groups sharing the spoils of military conquest, silk-road trade, and the taxation of others’ trade. This expansion was achieved by taking control of other kingdoms, city-states, and regions (by alliance or force) between the seventh and ninth centuries and ruling them as an empire with an emperor (btsan po) at its head. The term btsan po is difficult to translate but may be akin to the term