Denier Bracteate - Jakza von Köpenick

Jakza of Köpenick was a Hevelli Slavic prince who briefly seized Berlin-Köpenick from the Ascanian margrave Albert the Bear around 1150, an occupation that Albert ultimately reversed — yet Jakza retained enough local authority to strike his own coinage for roughly two decades afterward. The bracteate form itself, a single-sided thin silver striking, was the dominant penny technology in northern Germany and the Slavic frontier zones during this period, adopted by minor lords precisely because it required less silver per coin than a full denier.

Jakza's issues are among the earliest attributable to a Slavic ruler operating within the German monetary orbit.