I want to know the answer to the following question:
What influenced the consistency of the written Tibetan language?
All the background I'm provided with is that "This is probably due to the long-standing influence of the Tibetan empire, whose rule embraced (and extended at times far beyond) the present Tibetan linguistic area, which runs from northern Pakistan in the west to Yunnan and Sichuan in the east, and from north of Qinghai Lake south as far as Bhutan.". Is that enough to answer the question?
Answer: yes