Each zone had one special structure:
The north had the Northern Library, written in Ocean Elves' language.
The south had the Beast Stadium, written in Ancient Werewolf demi language.
The east had the House of Herbs, written in Monster Treant language.
The west had the White Pavilion, written in Centaur language.
Based on this, they concluded that in the past, each zone was populated by specific species. The White Pavilion and Beast Stadium were already accessible, so there was no need to find keys for them. However, the Northern Library and House of Herbs were closed, so keys were required to open them.
According to their recent discoveries, both closed structures shared the same set of keys.
Alexander drew circles on the maps created by the scouts, indicating the locations of the keys. He then projected the appearance of the keys so everyone would know what to look for.