I have a Theory on how equestria came to be. It was the distant future For US. Humanity was on the verge or nuclear war. In the final day's of humanity, A flurry of nukes were launched Decimating the human population. With Humans extinct, Either Through evolution or Genetic mutation caused by the high levels of radiation, Ponys Became The dominant species And the magic is just Remnants of advanced tech humans left behind.