Giants' Fall

Era beginning/end

A mysterious event causes all giants fall dead to the ground. Their skeletons remain to this day, some under layers of dirt and vegetation, others partly visible in mountains or waterfalls

It is impossible to say when this actually happened, as there were no people back then. All we know is that it happened, and the traces of them are to be seen. This marks the end of the era of giants, and brings us into the age of animals.