From [url]http://www.nanoda.com[/url]:

Setsugetsuki is a drama set in the Sengoku jidai (戦国時代) or Warring States period, so called because Japan was divided into many small, petty fiefdoms constantly at war with each other. It was a time of social upheaval, political intrigue, and nearly constant military conflict that lasted roughly from the middle of the 15th century to the beginning of the 17th century.