Nocturne

The Nocturne is the central stronghold of Imperator Ix and the Nocturnus Clan echidnas. It appears as the final area in Sonic Chronicles: The Dark Brotherhood.

Pre-Cage
During the Nocturnus / Knuckles Clan war on Sonic's world 4000 years ago, Nocturne apparently functioned as the capital of the Nocturnus Tribe. The Nocturne in its original form is shown briefly during a movie sequence in Sonic Chronicles, and appears somewhat similar to the echidna pyramid-cities ruled by Pachacamac in Sonic Adventure; ableit more advanced, with glass windows and waterwheels. This picture matches with Ix's comment that the Nocturnus "believed in science and industry, and we flourished". It is stated by Nestor the Wise that the Nocturne housed (and still does) the Nocturnus Tribe's Gizoid-production labs; as such, Emerl must have been 'born' there.

Argus Event
After the near-total destruction of the Knuckles Clan at the hands of Perfect Chaos, the Nocturnus echidnas "nearly colonized the whole world". However, just as complete global conquest was within their grasp, the Argus Event occured. Sonic Chronicles shows the Nocturne being torn out of the earth into a portal to the Twilight Cage.

At least some remnants of the global Nocturnus civilization survived on Sonic's world after the loss of the Nocturne; the movie sequence in Sonic Chronicles displays at least one echidna evading the portal. Emerl certainly avoided the cage, although Nestor states that "All others [the Gizoids] were accounted for". Whether the Argus Event systematicly devastated other Nocturnus centres as well, or whether the survivors dwindled to nothing and died out following the loss of their capital, leader, and military machinery, is unknown. The point remains, nonetheless, that whatever remained of the Nocturnus tribe outside the Cage did not survive.