I found this book written in 2009 by Shirin Akiner about
Religious Language of a Belarusian Tatar Kitab. They linked some old Tartar text to the Uyghur script.
The author also write about a drastic language shift in the middle of the 16th century among the Tatars that effected even their religious scripts.
Another author the author reference from 1558 says the Tatars he meet could not speak Turkic or Arabic but could talk Polish and Ruski.
And a Ottoman writer in the 17th century said that the Tatars spoke a Slavic language
Later in the book the author writes about the Tartars wrote mostly in Arabic letters that was modified to fit the phonetics of their language.
Uyghur Script:
Old Uyghur alphabet - Wikipedia
Text from book p69-72:
Religious Language of a Belarusian Tatar Kitab
Image of letters from book p89
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Also found this map from 1741 in a store
View attachment 45376