The phrase "ancient curse" refers to a spell or curse that has been around for a very long time. It usually carries a strong and lasting negative effect on the people it is cast upon. Full definition
The Kiss, an erotic horror film dealing with ancient curses and the occult, is the story of a teenage girl whose world is destroyed by the arrival of her mysterious aunt and the death of her mother. (rottentomatoes.com)
Framed as more of a superhero origin movie than ancient curse mystery, a messy plot unravels fast (theguardian.com)
Ubisoft has revealed that Assassin's Creed Origins, the upcoming Egyptian - themed title which is set to be revealed at E3 2017, will expose players to the «terrible, ancient curse of Khnumhotep The Undying». (pointandclickbait.com)