Time perception is altered, but putting a figure like '14000 years' on it is plain ridiculous.
Jim DeKorne did describe in his book, "Psychedelic Shamanism", having the experience of living the entire lifetime of another person and while that wasn't with the use of a classic serotonergic psychedelic it does correspond to the decades of your NDE. 14000 years would be well over 800 generations.
“There is a way of manipulating matter and energy so as to produce what modern scientists call 'a field of force'. The field acts on the observer and puts him in a privileged position vis-à-vis the universe. From this position he has access to the realities which are ordinarily hidden from us by time and space, matter and energy. This is what we call the Great Work."
― Jacques Bergier, quoting Fulcanelli