One hears all sorts of explanations for the origin of prayer wheels. A popular version has them descended from revolving sutra cases.
Sounds reasonable, but who knows?
The first revolving sutra case of which I am aware is from the Liang (500 - 550 CE). There is also one from the early or north Sung (960 - 1126 CE), the Chuan-lun-tsang Tien. This is nicely documented in Liang Ssu-ch'eng's remarkable Pictorial History of Chinese Architecture, which I highly recommend. You can also find a discussion online at the China History Forum. One also finds them elsewhere in Asia, such as Japan's Kamakura Hasedera rotating case, above.
Well, lets take a deep breath... we have the Kangyur in 103 volumes, yes? The Tangyur in 213? I am talking the big, fat Derge edition. We have 63 volumes of the Rinchen Terdzo.... catch my drift?