The event occurs within the trilogy titled The Southern Reach, in an area of the U.S. that seems to be somewhere in the State of Florida, including one or two nearby islands. The event is considered to be the creation of a corridor of land surrounding Area X which is named The Border.
The event is believed by various characters and organizations on Earth to have taken place in the mid-1990's, twenty years previous to the time during which some of the main characters of the trilogy are describing or being described as investigating and/or participating in researching the cataclysm of the event, as well as the area within The Border known as Area X. It is believed that advancement of The Border and Area X which it contains, threatens the existence of the Earth. The trilogy follows the event before, during, and after The Border creation, and does so by examining various characters' experiences surrounding that event, as well as the experiences of a number of expeditions of military and scientific personnel across The Border and into Area X.
Approximately 1500 people living in a small working class village and its environs were believed to have been destroyed during the event. The event is regarded as having occurred as an attempt by an unknown entity to possibly contain the advancement of Area X. Area X, and its border, are under the observation of a joint intelligence and scientific agency which has been named The Southern Reach. The military is also involved with security and maneuvers regarding The Border, Area X, and various personnel in all three areas who are, or have been involved with The Border and Area X. The community of scientists and intelligence agents working within the agency work in a building that is also known as The Southern Reach, and is approximately 20 miles away from The Border and Area X, both of which are guarded by the Military via a variety of checkpoints manned by military personnel.