Modern era

is a term used loosely to describe the time period from which Kagome Higurashi originates, 500 years in the future from Inuyasha's search for the Shikon Jewel during the Sengoku jidai. Kagome and Inuyasha are apparently the only people who can travel between the two worlds, which they do through the use of the Bone-Eater's Well. Kagome returns periodically from the past to play catch-up at school, but she eventually leaves it behind permanently to live with Inuyasha. In the modern era, yokai no longer exist and are considered a myth as they had went extinct centuries ago.

Trivia

 * Swords of an Honorable Ruler implies mons seem to go exctint around 300 years before the Modern Era. It's possible there was a mass extermination or they simply hide themselves as humans.