"Ero" is a colloquial word, an ethnic "nickname" referring to a person from Herzegovina, and in Western Serbia it was used specifically in reference to the large number of immigrants to the area who came from Hercegovina during Ottoman rule, forming a distinctive ethnic group there.

The adjectival form (neuter) of Ero is "ersko," and is here used with the neuter noun "kolo": "ersko kolo" (literally 'Hercegovinian kolo', but in this case connoting "kolo originating with the ethnic group whose members are called 'ero'").

Ersko kolo is done to the melody of a folk song entitled "Ja idok" ('I walked'), which often replaces Ersko kolo as the name of the dance.

During World War II, Ersko kolo was picked up by all the embryonic KUDs and became standard repertoire, in a number of variants. I learned it in 1952 from dancer Miodrag Vukovic', Belgrade, and brought it to the United States. The Duquesne University Tamburitzans recorded it (without lyrics) in 1954 on Michael Herman's Folk Dancer label, and I introduced it at the Stockton Folk Dance Camp in 1955.

Note: "KUD" means Kulturno-umetnička društva (Cultural-Artistic Society), a state-sponsored folk group founded for the preservation of national folk music and dance, as opposed to being for entertainment purposes.