Tanka - Jahanshah countermarked type

Jahanshah ruled the Qara Qoyunlu — the Black Sheep Turkmen confederation — at its greatest territorial extent, controlling Azerbaijan, Iraq, and much of Persia. His death in 1467 at the hands of the Aq Qoyunlu (White Sheep) ruler Uzun Hasan effectively ended Qara Qoyunlu dominance over the western Iranian plateau. Countermarked tankas of this type reflect the administrative chaos of that final period, with existing coinage overstruck to assert legitimacy as control over mints changed hands rapidly.

The countermark practice here is documented in Album's corpus as a transitional monetary measure rather than a standard issue.