The Prehistoric World (at the time of the Worldshaping) was shrouded in fog and devoid of all plant life, save for the Eldertrees, inhabited by the few Yalid races. Illumination was provided by the moons El-Asil and El-Duram, while the Sun was far dimmer than it is today
Prehistory is the blanket term for the time before Beld created Beldkind and they began to count years. By definition, the length, events, and scope of Prehistory is entirely unknown. It is believed that the Worldshaping caused some sort of loss of memory regarding Prehistory, as none of the Yalid have any memory of the event or records (the existent records having been literally wiped clean) even though all of the living Nephilim were present for the Worldshaping.