Bishoujo Senshi Serra Muun
(Pretty Solider Sailor Moon)
This is the story of the ones that most know as the Sailor Scouts.
Long ago when the Earth only had only one contnient there was a beautiful kingdom on the Moon. It was located on the moon at "Mare Serenitatis" which is the "Sea of Serenity". There ruled a beautiful woman named Queen Serenity. On the Earth she was known as Selene, the Goddess of the Moon. The kingdom that she ruled was called the Moon Kindom during the Silver Millennium. It was a very peaceful and a happy place. This moon kingdon was also very advanced then the Earth and its people were known to live longer lives. Queen Serenity had a daughter named Princess Serenity. The Princess was protected by four female warriors called the Sailor Guardians. The Sailor Guardians were princesses of their respective planets. While they were on the moon watching over the Moon Princess the princesses of another group of four female warriors was protecting the outer parts of the Solar System from intruders. They were called the Outer Senshi. They were princesses of their own respective planets as well. At this time, the whole universe was in peace. It was called The Silver Milliennum. But soon this peace would end because of pure evil.
(The Sailor Senshi)
The princesses that protected Princess Serenity were: Princess Minako, Rei, Ami and Makoto (Mina, Raye, Amy and Lita). When they transform into Sailor Senshi they protect the princess with the Legendary Stone Sword which is seen used by Sailor Venus. At other times, they are also Princess Serenity's friends.
Queen Serenity would teach her daughter many things about being the next ruler of the Moon Kingdom since she was the last heir. But lately she has fallen in love with the prince of the Earth named Prince Endymion(Prince Darien). He was a good and well respected man on Earth. He also had his own honor guards called The Four Generals (Jedite, Nephlite, Zoizite, and Kunzite). Princess Serenity sometimes would go to Earth secretly to see him knowing that it was forbidden for people of the moon and Earth to make contact with each other. She would say that the gods forbid it for them to be in love but it was too late.
Soon from the Sun there was this strange activity going on there. That activity lead to the Moon Kingdom's destuction was called The Evil One and went to attack the Earth first. It wanted the power of the Ginzuishou(Silver Crystal) and stole the hearts of the humans using their desire for long life and controled them. This is probably how the people of the Negaverse began.
Soon a woman that was jealous and angry about Prince Endymoin being in love with the Moon Princess became someone called Queen Beryl. Then she turned the Four Generals against their master, Prince Endymoin, to be in the Negaverse. One night where there was a big party on the moon with an eclispe. Soon on that night the Negaverse came to the Moon Kingdom and began to destory it. The Prince fought aganist them along with the people of the moon. Then while the prince was protecting the princess he got killed by Queen Beryl right in front of the princess. After that(in manga only) she takes a sword a stabs herself to death. From Queen Serenity watching this, her own daughter commiting suicide, she reacted in sorrow and did what she felt was right. She felt like she was doing the right thing but since she wasn't thinking straight so she couldn't use the Ginzuishoun to it's fullest. So when she finally managed to seal the Evil One (Queen Metallica) and the Negaverse away it wasn't sealed completely because of this. Also, she used the last of her power to have the people of the moon reborn to a future Earth. Then she died while later the main computer of the Moon Castle stopped working, made the sub-computer boot up and left her will in a form of a hologram of herself. Meanwhile on Earth, the Earth Kingdom was destoryed as well "and mankind had to begin anew in its development..."
Thus, the story of the Sailor Senshi that you already know of started from this...