tl;dr Megan is a goddamn WIZARD
There are few alive today who are privy to the mysteries of the Crystal Empire, its histories and secrets relegated to dusty tomes and elusive archives. Stories of the Empire's founding muddle with myths and legends, and no single figure is more mysterious than the first and only Crystal Queen.
While there are no definitive consensus on her origins, most agree that the Crystal Queen was a very powerful wizard who went by the name of Meaghan the Bright before ascending to the throne. She ruled as Queen for nearly 500 years from circa 800 y.b.b. to circa 320 y.b.b., and at the height of its power the Crystal Empire stretched across every continent of the world, its Imperial Capital a shining beacon of power. She entrusted the governing of the Empire's colonies to her loyal Justiciars: female officers of her inner council and close friends with whom she shared her vast knowledge of magic.
The Crystal Queen disappeared from records as mysteriously as she had appeared. In circa 320 y.b.b. Meaghan vanished suddenly, leaving the Empire without a Queen. Her Justiciars shared the duties of ruling the Empire amongst themselves, and took up the title of Princesses.
The next 310 years (circa 320 y.b.b. - 10 y.b.b.) saw the Empire's colonies flourish into powerful dominions in their own right. Their prosperity was sadly in stark contrast to that of the Imperial Capital, which had become increasingly weak amidst internal power struggles and decay, finding itself unable to exert any meaningful influence on its colonies.
From circa 10 y.b.b., the weak and fractured Capital was rocked by turbulent uprisings and invasions, culminating in the unicorn Sombra enslaving its populace and prompting a siege on the Capital by the combined colonial armies in retaliation. Sensing defeat, he cast a curse on the city, snuffing out its once proud light. With that, the age of the Crystal Empire finally came to an end.