How old was Merlin when he died?

Question

There are many different accounts of the life of Merlin, one of the noted magical figures in the tales of King Arthur. Some accounts do not cover the end of his life, while others state that he died at the hands of the Lady of the Lake or by Niviane, his lover.

How old was Merlin when he died? I'd like to focus on these two instances, as they are the most commonly cited myths which I have been able to find. The one source I have found is Vulgate Merlin, as explained here, though it states that Niviane was also known as the Lady of the Lake - yet not the same as the Lady of the Lake who bore Excalibur to King Arthur!^*

^{*This may lead to another question. . .}

Answer 1

Geoffrey's account of Merlin Ambrosius' early life in the Historia Regum Britanniae is based on the story of Ambrosius in the Historia Brittonum.

The Historia Regum Britanniae explains that when Merlin died he was "400 Summers his Lord" (His Lord would be Arthur and Arthur died in his 40's to 60's). So we can assume that Merlin was around 440-460 years old.

However his character was based on Myrddin Wyllt. Myrddin died at the age of 39.