Based on the clue 'by the 15th c this city was capital of the russian...', what is the answer?

Based on the clue 'by the 12th century the chinese had harnessed magn...', what is the answer? Based on the clue 'by the 12th century the chinese made one of these ...', what is the answer? What is associated with: by the 1300s knights were losing importance in warfare due to growing use of this explosive? Based on the clue 'by the 15th c these songs went from one voice or p...', what is the answer? Based on the clue 'by the 15th century knights just werent that impor...', what is the answer? What is associated with: by the 1871 treaty of frankfurt france gave germany alsace part of this quiche making province? What is associated with: by the 1920s balenciaga was the leading couturier in this country his homeland? What is associated with: by the 1950s scientists were able to do this to frogs mice followed in the 80s?