Pretty much all of the events that happen in this book happened in Genesis: all of the characters are the same, all of the places are the same, and the general gist is the same. Just check out the chapter summary of Genesis in our Bible guide.
But this isn't just a retelling of Genesis. The Red Tent is told through Dinah's eyes. In Genesis, she's the daughter of Jacob who gets raped and whose family then takes vengeance.
Well, at least that's what Genesis says. The Red Tent begs to differ. See, through Dinah's eyes in this book, she didn't get raped; she fell in love. Meanwhile, everything happening around her—Joseph being sold into slavery and becoming a high-up Egyptian, Jacob dying, her mothers dying—actually happened in Genesis. But all of these events have a different twist to them because they're told through a certain character's perspective.
What Anita Diamant does in The Red Tent is take biblical events and transform them into her own unique story, all the while keeping most of the biblical details intact. And that's how historical fiction works, folks.