No clear definition exists for the origin of the Indo-European languages. Some scholars theorize that it came across the plains north of the Black Sea with a kurgan culture around 2500 B.C. According to the theory, the first such kurgan invasion was successful in the Balkans, where it spread to central Europe. | No clear definition exists for the origin of the Indo-European languages. Some scholars theorize that it came across the plains north of the Black Sea with a kurgan culture around 2500 B.C. According to the theory, the first such kurgan invasion was successful in the Balkans, where it spread to central Europe. |