Verily, thus saith the Lord unto you concerning the Apocrypha — There are many things contained therein that are true, and it is mostly translated correctly; There are many things contained therein that are not true, which are interpolations by the hands of men. (Doctrine & Covenants 91:1-6)
The history of the Enochian Age has been all but obliterated in our times. Scholars scoff at the idea of a true civilization--working metal, building great cities--during the Pleistocene Epoch. All traces of their mighty towers have been lost to the sea after the cataclysmic rise of sea levels during the Flandrian stage 12,000 years ago. The only records that survive are the muddled oral reminiscences which became part of the religio-historical heritage of the Ancient Near East. Therefore, no one really knows the story of the Enochian Age
And Cain knew his wife in those days, and she conceived and bare a son, and he called his name Enoch, saying, In that time the Lord began to give him rest and quiet in the earth.
And at that time Cain also began to build a city: and he built the city and he called the name of the city Enoch, according to the name of his son; for in those days the Lord had given him rest upon the earth, and he did not move about and wander as in the beginning. (Book of Jasher, 1:34-35)
Some 15,000 years ago, humanity began it's long ascent to mastery over the Earth.This was due to the Children of Cain, the Kaiyinim. This strange tribe wandered east of Eden and came to rest in the Riverlands of Senaar. In their wanderings, the Kaiyinim had acquired terrible secrets and become the wards of the Demons of the Earth, the Watchers. And not just wards, for it was said that the Children of Cain lay with the Fallen of Heaven and produced a race of monsters. Under the tutelage of their eldritch patrons, the Kaiyinim learned the Arts ands Sciences, which were unknown to the rest of humanity. And, so, it was a simple matter for them to conquer and enslaved the natives of Senaar.
Flush with conquest, the Kainyim built a fantastic city, the first city in the history of the world, and named it after Cain's firstborn: Khanok. There, atop the Carnelian Throne reputed to be a gift from the arch-demon Semyaza, the Overlord of the Kaiyim ruled the lands of Senaar. They taught some part of their arts, such as bronze-working and writing, to their subjects who, in time, began to fashion cities for themselves.
But the blood-thirsty success of Cain's Children was also their undoing. Whether they explored darker and darker corners of knowledge or simply basked in the opulent hedonism availble to them, the Kaiyim became isolated, insular, and decadent beyond imagining. The Armies of the Carnelian Throne seldom left the City of Khanok, tribute went uncollected, and infrations upon the Enichian social order went unpunished. Eventually, the fearsome Children of Cain began to pass into legend. The people of Senaar were left with an advanced civilization, powerful sorceries, and a culture of conquest, without any force to contain them.
The end of the Enochian Age wasn't pretty.