Sui Yangdi
The best-known medieval Chinese name for Tibet is "Tubo" (; or , or , ). This name first appears in Chinese characters as in the 7th century (Li Tai) and as in the 10th-century ("Old Book of Tang", describing 608–609 emissaries from Tibetan King Namri Songtsen to Emperor Yang of Sui). In the Middle-Chinese language spoken during that period, as reconstructed by William H. Baxter, was pronounced "thu-phjon", and was pronounced "thu-pjon" (with the "" representing tone).