The Sana'a manuscript was discovered in Yemen in 1975, it is very old with no dots and vowels.  It is a palimpsest (It has two layers of writings). It had late 7th to 8th century scripts.  It was carbon tested at the university of Arizona in 2007, and was dated to mid 7th century. The same segment was taken to four Europeans labs and they did not agree with the Arizona dating.  Shoemaker concludes that there is a problem with the carbon dating because the process dates the skin of the animal not the time the writing was written

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