Why not many years ago?

[v0031]

Many moons ago, it took an age to send someone a message. Today, we have the Internet. We can instantly send someone on the other side of the world a message using email. One message that arrived earlier this week was not so instant.
A letter was mailed from the English city of Bath in 1916. It then got lost in the post. It was finally delivered 107 years later to an address in London.


The red seems odd to me.

[muon2]

Many moons ago is an idiom that just means a long time ago. Many sources attribute the phrase to the initial encounters between Europeans and Native Americans. Many Native cultures used the lunar month instead of the solar year as their principal means to tell time longer than a day, and they would count moons not years. The phrase stuck, in part because the English word month shares a root with moon.

[°Leprechaun]

Muon2 is right, of course.
Many years ago or a long time ago would be just as good, also.