Horseman right, holding a sword, Cyrillic circular legend КИАZЬ ВЕЛНКН ВАСНЛЕI ("Grand Duke Vasiliy") / Three knotted decorations, arabic "al-Sultan Tokhtamish Khan khalad..." ("Sultan Tokhtamish Khan, (may his rule) endure"). 17mmx14mm, 1.00 grams. Moscow mint, struck in the 1390s. Guletsky/Petrunin #138C.
Very rare early Russian coin - it is rated R3 in Guletsky/Petrunin. Interestingly, the reverse references the Mongol overlord of Russian, Khan Tokhtamish.
Ex-Gorny and Mosch (without ticket).