The scholar Jean Devise has traced the earliest uses of a Moor or a black figure in heraldry to Bavaria, the upper Rhineland, and Lower Saxony in the late thirteenth and early fourteenth centuries. The use in family and institutional crests at this time most likely reflected the spread of the imagery of the Hohenstaufen emperors, as in St. Maurice and the Black Magus, in which black figures stood in for the universalist pretensions of the Church and the Empire.
The illustrator of a fourteenth-century catalogue of coats of arms, known today as the Gelre Armorial, invented a coat of arms for the Three Kings/Magi to accompany the crest of the Archbishopric of Cologne, site of shrines to the Three Magi and to St. Maurice. The crest for a black Balthasar, which features St. Maurice and his spear, was influential in spreading the image of a black figure as a symbol for the reach of Christianity.
Source: Gelre Herault d’Armes (ca. 1370-1395), Bibliotheque Royale Albert Ier Ms. 15625-5, fol. 28v.