I think he meant dryas which would make much more sense.I did a little research about dryas and here is what I found.

Dryas is the name of several climatic periods, which were named for their abundant dryas flowers, that can grew in that time period so you could say for plants a will that lived on and couldn't be hold down. These periods are known for an abrupt climatic cooling event, which would also fit the description of OP with the ice age. But that's not everything, if you remember the Im scene in Pangaea castle in the flower room there were flowers which resemble a bit the dryas plant. And we see Im holding his finger up and a butterfly lands on it and we see several other butterflies flying around. The reason I wrote this is because there is a butterfly species called dryas iulia. And what got me the most is the fact that there is a species of monkeys called dryas monkey. A little-known species of guenon found only in the Congo Basin. We know whose "family" name is monkey. For now I am fully convinced that the D. stands for dryas.

Edit: In those time periods one is also known as younger dryas, which is also known in conspiracy theories as a time the world was technically more advanced than now (building of the pyramids, atlantis etc.) and the knowledge was lost and what happened is held secret by the governments and politics --> void age

In addition to that, there are also several princes in greek mythology with the name dryas, so even the prince theory would fit.