A good research topic will be
- Specific: you can deal with it in the short space of your paper
- Researchable: there are primary sources, books, and scholarly articles on the topic
- Factual, not depending on personal opinion: you can demonstrate the correctness of your thesis
Examples:
Ancient Greece -- Economics -- Trade with the Black Sea region -- Trade with the Black Sea region before the first century B.C.
Ancient Greece -- Science -- Medicine -- Diseases -- Malaria -- Occurrence and treatment of malaria in Greece up to the first century A.D.