I want to know the answer to the following question:
When did the name for Tibet, Tubo, first appear in Chinese characters?
All the background I'm provided with is that "This name first appears in Chinese characters as 土番 in the 7th century (Li Tai) and as 吐蕃 in the 10th-century (Old Book of Tang describing 608–609 emissaries from Tibetan King Namri Songtsen to Emperor Yang of Sui).". Is that enough to answer the question?
Answer: yes