Where it all began

In the village of the hidden leaf, the leaders were called hokages and the fourth hokage named Minato and her wife, Kushina, were soon to have a son

Because Kushina she was a junchoriki(this are people who have tailed beast in them)of the 9 tailed fox;Kuruma. It was too dangerous for her to deliver in the village for the seal will get weakened, so the fugal lords gave an order for her to be taken somewhere out of the village to have her kid not knowing what awaits them.