Context: South Slavic historically formed a dialect continuum, i.e. each dialect has some similarities with the neighboring one, and differences grow with distance. However, migrations from the 16th to 18th centuries resulting from the spread of Ottoman Empire on the Balkans have caused large-scale population displacement that broke the dialect continuum into many geographical pockets. Migrations in the 20th century, primarily caused by urbanization and wars, also contributed to the reduction of dialectal differences.

Question: What is a dialect continuum?
Answer: each dialect has some similarities with the neighboring one, and differences grow with distance.

Question: What caused the dialect continuum to become fractured?
Answer: migrations from the 16th to 18th centuries resulting from the spread of Ottoman Empire on the Balkans

Question: Contrary to the 16th and 18th centuries, what caused migrations in the 20th century?
Answer: urbanization and wars

Question: What did the spread of the Ottoman Empire in the 20th century contribute to?
Answer: Unanswerable

Question: What are two characteristics of urbanization?
Answer: Unanswerable

Question: What did the Balkans create historically?
Answer: Unanswerable

Question: What did wars cause from the 16th to 18th centuries?
Answer: Unanswerable

Question: What broke urbanization into many geographical pockets?
Answer: Unanswerable