The Old Uyghur script descended from the “Uyghur” version of the Sogdian script, and was used from around 700 AD to around 1700 AD. Woodblock printing and movable type printing was developed by Uyghurs in around 1250, around 200 years before Gutenberg’s printing press. This makes Old Uyghur probably the earliest script to be printed with movable type. Indeed, there are a large number of books in Old Uyghur found in Turfan, where movable type was developed.
Fear not, Euro-chauvanists: Gutenberg still has a lock on the development of the printing press. While information is sketchy, it seems that Uyghurs placed the type face-up, inked it, laid a piece of paper down, and rubbed the paper to transfer the ink — a much slower process than running a press.
Old Uyghur had two principal differences from the Sogdian script
- They almost never left out the vowels, even the short ones (making it even closer to an alphabet than Sogdian).
- They rotated the whole language counter-clockwise. The characters are written top-to-bottom, left-to-right, and the characters are also rotated 90 degrees from the Sogdian. Old Uyghur is one of the few languages that is written vertically.
It is surprisingly common for glyphs to rotate by 90 degrees over the course of their lifetime (or when being borrowed), or to flip (especially when the writing direction changes). It is less common for the direction of writing to rotate by 90 degrees. There are probably two or three PhDs to be written to explain why many scripts rotate the glyphs and why Old Uyghur scripts rotated the whole line of writing.