When did CKB come out?

Could you please enlighten me on the timing of CKB's emergence? When did it first appear on the scene? I'm quite fascinated by this cryptocurrency and its potential, but I'm not entirely sure about its genesis. Could you possibly provide me with a specific date or a time frame during which CKB was introduced? It would greatly assist me in understanding its historical background and development trajectory. Thank you in advance for your clarification.