Complex sentence: However, the League faced great difficulty with the growing tensions between the Russian Empire and Austria-Hungary, mainly over the Balkans, where the rise of nationalism and the continued decline of the Ottoman Empire made many former Ottoman provinces struggle for independence.
Split into simpler sentences: However, the League faced great difficulty with the growing tensions between the Russian Empire and Austria-Hungary. These tensions revolved mainly over the Balkans where, with the rise of nationalism and the continued decline of the Ottoman Empire, many former Ottoman provinces struggled for independence.