Which African landlocked country is known for its diamond mining?

Which landlocked country is home to the ancient city of Samarkand? Which of the following countries is a landlocked country in Southeastern Europe? What is the world's largest landlocked country? Which landlocked country in Central Asia has the highest population? Which of the following European countries is landlocked? Which African country is both landlocked and has the highest average elevation? What is the name of the only landlocked country in Southeast Asia? Which landlocked country in Central Asia was once part of the Soviet Union?