Final answer:
Albania is the country located on the east coast of the Adriatic and Ionian Seas, between Greece and Montenegro, known for its mountainous terrain and history of political and economic challenges.
Step-by-step explanation:
The country located on the east coast of the Adriatic and Ionian Seas, between Greece and Montenegro, is Albania. Romania, Bosnia & Herzegovina, Serbia, Montenegro, Kosovo, Macedonia, and Albania are countries situated in the Balkan Peninsula, which was once part of former Yugoslavia. Albania is known for its rugged mountainous terrain, and it has a history of poverty and political turmoil, including receiving Communist support from China. Following the breakup of Yugoslavia in the early 1990s, Albania has faced challenges in integrating with the rest of Europe, particularly after the war in Kosovo.