original_query: According to Jean W., what caused the near disappearance of Bulgar Turkic?
query: According to Jean W. Sedlar, what caused the near disappearance of Bulgar Turkic?
answer: According to Jean W. Sedlar, the complete abandonment of Bulgar Turkic by the ruling class in favor of Slavic, following their conversion to Christianity and Slavicization in the mid-9th century, led to its near disappearance, leaving no trace in Old Slavic texts.