At the edge of our positive-matter universe exists an energy source of unimaginable power. This edge is ever expanding, slowly encroaching on the Negative Zone universe.
Shortly after our universe's creation event, "The Kyln" was constructed to harness this energy. The energy was harnessed to server as a power source for over 200 planetary systems.
The architect of these interconnected spheres is unknown, but it is safe to assume that its secondary function was not in the original blue prints. Likely the first to utilize the Kyln as a prison, Galactus decided this power plant would be an effective holding cell for his primary enemies: Aegis and Tenebrous. Over time, it became the default maximum security prison for the universe, protected by the Omega Core and religiously maintained by clerics who view the Crunch as a holy site. Sections of the Kyln are reserved for religious devotees who make pilgrimages as a sign of their faith. Three more of the most notable prisoners are: The Maker, Skreet and the Fallen One.
Thanos visited the Kyln at the Crunch as a pilgrim. After a little trouble with the Omega Core, he was granted access. After a visit by Death (envisioned as a young girl) he joined the fight against The Maker (after a riot set her free). This conflict caused major power outages, which then allowed the Fallen One to escape. Thanos allied with Skreet and eventually mentally enslaved the Fallen One, making him his herald. These relationships would surface again during the Annihilation story arc.
During Annihilation, the Annihilation Wave entered the positive-matter universe through the Crunch. Upon doing so, their first act of destruction was to tear the Kyln apart, causing mass casualties to inmates and Omega Core alike; it also facilitated the escape of some of the Kyln's most dangerous inmates, including Aegis and Tenebrous. On Annihilation Day, Plus 206, Aegis and Tenebrous were leveraged by Thanos to capture and subdue Galactus and the Silver Surfer.
Annihilation Day, Plus 281
A freed Galactus (since Annihilation Day, Plus 220) assigned the Silver Surfer (freed on the same day) the task to locate Aegis and Tanerbrous. It didn't take him long to find the duo, at the Crunch, searching through the Kyln debris for ancient allies. After signaling for Galactus, Silver Surfer decided to distract the two cosmic powerhouses until his arrival. Before long, Silver Surfer was completely overwhelmed, but decided to do what it took to keep Galactus' greatest foes at bay.
In a final effort, knowing that it would likely kill him, he charged into the Crunch, surfing on its surface, disrupting it enough to spill off onto Aegis and Tenebrous. As Galactus arrived at the Crunch, he witnessed the inconceivable -- a lowly herald took down a pair of Proemial Gods -- Galactus was avenged. After being the location of their captivity for countless millenia -- since the creation event and their capture by Galactus; the Crunch became the final resting place for Aegis and Tenebrous as it continues to expand into the Negative Zone.