Byzantine chroniclers read Islam through biblical genealogy and Jewish conspiracy

Evidence

For Theophanes, Muhammad, “the leader and false prophet of the Saracens,” is important enough to merit a brief biographical sketch. Like Isidore, Theophanes sees biblical genealogy as a key to understanding the Arabs’ (or anyone else’s) place in the divine plan: he says that they are the descendants of Ishmael through Nizaros. Theophanes claims that the Jews had first flocked to Muhammad, thinking he was their long-awaited Messiah; when they saw him eating camel (a forbidden food), they realized their error, yet some of them stayed with him out of fear “and taught him illicit things directed against us, Christians.” — John V. Tolan, Saracens, 407

Categorization

• XREF: The Jew-teaches-Muhammad claim is a direct medieval ancestor of modern ‘Jewish background of Islam’ conspiracy tropes; genealogy via Ishmael repeats Isidore and maps onto vault-reading of how Islam was framed as derivative.
• QUESTION: Does Theophanes’s double move — Ishmaelite descent legitimating Arabs in scripture yet framing Islam as Jewish-taught heresy — anticipate the modern deradicalization/derivation reflex?