Pan-Slavism, or the belief the populations from Eastern Europe should form their own nation, was a powerful ideology that started during the end of the 19th century. At the time, there was a strong sense of nationalism, which was the belief that a country's culture was superior to the others, among Europe.
Slavic nationalists struggled due to their strong opposition to the Austrian-Hungarian Empire and its control over the region. This group strongly disapproved the annexation of Bosnia and Herzegovina to this empire and this started a series of conflicts that would lead up to the first world war.