One day Toadsworth, the steward of the Mushroom Palace, was wandering along the Dire Dire Docks, when he noticed something floating in the water. It was a basket, and inside he found a baby girl inside. The girl was human, but no one in the Mushroom Kingdom had ever seen a human before. No one knows where she came from, and it remains a mystery to this day.
They named the girl Peach, and the king of the Mushroom Kingdom adopted her, making her a princess and the heir to the Mushroom throne. Peach grew up and lived a happy life, but then tragedy struck.
A toad, bloody and barely hanging onto his Yoshi's reins, galloped to the gate of the Mushroom Kingdom. The guards rushed to help him, but it was too late. "Bowser... is... back..." were his last words, as a bubble of blood popped in his mouth, and the last remnants of life escaped from his eyes.
After nearly a hundred years of peace, Bowser, the Koopa King, had returned.
A brave and proud man, the Mushroom King set off with troops to stop Bowser, but unfortunately he met his end at the hands of the dinosaur tyrant, and with his tragic end Peach became the ruler of the Mushroom Kingdom.
Although having suffered repeated kidnapping attempts by Bowser and his forces, Princess Peach is a survivor, and it's not unheard of for her to fight along side Mario and Luigi, the protectors of the realm.