Prologue
The hidden ninja villages were quite well known for their skilled shinobi and combat. One village was exalted above the rest, that village was known as the Village Hidden in the Tree Leaves, or Konohagakure no Sato. Not much is known about these villages except secrecy was their key to life. Other things are concluded by evidence. There was believed to be 5 major villages and various assorted smaller villages. A hidden village was their parent country's main source of economy and maintained the economy by training ninja at a young age to perform missions. They also serve as a parent country's military force. The leaders of the villages are called Kages, they also have an equal status as the leader or ruler of their parent country. The five countries are the Land of Fire, the Land of Earth, the Land of Lightning, the Land of Water, and the Land of Wind. Their respective hidden villages were Konohagakure(already mentioned above), the name of the Land of Earth's is not known, Kumogakure, Kirigakure, and Sunagakure.
About 500 years ago though, the villages were taken over by a conquering civilization that for it's small size was quite powerful. The conquerors used weapons unknown to the ninja. After a few years of war the ninja population was severely depleted. A few more years and the conquered ninja did not have enough people to continue the war. With this disadvantage most ninja villages were made to surrender and the ninja population died out completely.
Myths say that a select group of ninja survived and went into hiding. A rumor surfaced that most of the ninja of Konoha had survived by the sacrifice of their Rokudaime Hokage as he went to negotiate his peoples' release with his freedom. The leaf ninja saddened at the loss of their powerful leader gave up the ways of ninja, or so it seemed. Quite a few were taught in secrecy. Nevertheless, the ways faded until very few knew of the old ways, or of the great sacrifice made by their ancestors' leader. The only remaining remembrance was a festival held every year on the day believed to be his birthday, October 10. There is evidence that points to their being another reason for this festival too, but it is uncertain what it was.
Time passed and everything was peaceful. The conquerors had returned to their land in the west to settle down. Missed by all but the four leaders of those people was the captive they had brought along with them. A young man no older than 18, but his prowess and power were already renowned throughout the other ninja villages. A young man called the Rokudaime Hokage. No one exactly knows what became of the man since the only evidence he even came to the west was a mention of it within the journals of two of the founders of Hogwarts'. The conquerors were known as wizards and witches. The reasons they went to these hidden villages are unknown.
-Excerpt from History of the Founders of Hogwarts' School of Witchcraft and Wizardry
Please R&R to tell me what you think. Most of the information I found at wikipedia.