5 Para - Petar I

Yugoslavia's first coinage issue, struck in 1920 as the newly unified Kingdom of Serbs, Croats and Slovenes scrambled to replace the patchwork of Austrian, Hungarian, Serbian, and Bulgarian currencies still circulating across its territory. The zinc alloy was a practical concession — copper and nickel were still in short supply across postwar Europe, and zinc had proven serviceable as a wartime expedient by multiple belligerents.

The KM#1 designation is apt: this is literally coin number one for a state that had existed for barely two years.