Before the rise of Starfleet, billions of years before life began on Equus, The Dimensional Universe was the realm of the first ones who rose to sentience.This race was the first to travel into the stars and spread across the cosmos. This race did not give their names, not even saying it on their documents, but to many, they were only known as The First Civilization.

These beings appeared only two Billion years after the Creation of the Dimensional Universe. from what little is known of them, from their sculptures that survived the eons, the First Civilization were Humanoids with elongated heads, long wispy hair, large eyes and insect-like mouth parts. One thing common in their culture is that they never wrote anything other than Math and Physics equations on their documents and monuments. it appears that their whole race was obsessed with Mathematics and Physics to the point that they did not even write down the name of their Race

It was They who called the Universe 'Dimensional' as they believed that the Universe was of Four Main Dimensions: three Spatial dimensions and the Fourth being Time. This is the reason many races, such as the Unicornicopians call their Universe 'The Dimensional Universe'

The First Civilization lasted until well over 12,000,000 years before The Birth of Equestria. It is unknown what happened to them.