This article examines the origin and genre of the parody legend of Isakhara/ Sahara, the Horde prince ("an honourable man of royal descent"), an ancestor of the Zagryazhskys'. Only one copy of it survives today - its text was inscribed on blank leaves of an early seventeenth- century manuscript. As far as can be judged, this legend was not widely circulated in the manuscript tradition; no direct quotations, reminiscences or allusions have been found to indicate familiarity with it. It is assumed that the text in question is a parody of the Zagryazhskys' genealogical legend, as it is presented in the genealogical record submitted by this family to the Chamber of Genealogical Affairs of the Order-in- Charge of Prikaz on 5 June 1686. With the introduction of several interpolations, the genealogical legend was transformed into a kind of historical anecdote, all the characters of which began to appear either pitiful or unpleasant. Both the dating of the text in question (end of the seventeenth century) and its content suggest that it could not have appeared in the proceedings of the mestnichestvo; its author was not guided by the practical purpose of the mestnichestvo, but by the motivation of a writer prone to social satire. This distinguishes the text under consideration from the line of genealogical pasquils generated by the principles of mestnichestvo of service organisation and allows to take anew look at the genesis of the genre of historical anecdote, the emergence of which in Russia is attributed by researchers only to the Catherinian era.