Strumica is the largest city in eastern Macedonia, near the Bulgarian border. Petorka, meaning “in fives”, refers to both the 5/8 meter of the dance, and the five times the basic pattern is danced.
Strumicka Petorka was introduced to North America in 1976 by Bora Gajicki, who in the 1960’s was a solo dancer with Ansambl KOLO, Serbia’s professional touring folk dance troupe. Bora arranged traditional Macedonian steps to match the 1972 recording of Strumicka Petorka, (attached below) the music most folk dance groups use today.
Here’s a link to a rather primitive video showing Bora himself demonstrating the dance.