Continuing with CORE Lore, #5 defines the convergence and how long ago it occurred.

Arthadian Anthologies @msarthadian

#CORELore 5: The Convergence is the term that references the birth of the CORE. This event occurred approximately 16 millennia before the current time. #newexpandinguniverse #scififantasy

11:20 PM ∙ May 28, 2022

In the CORE, time is determined by cycles. So when it is said 16 millennia, that is in cycles not years. If we said years, it would be approximately 32 millennia.