Dante used many common tropes of his time when describing hell. We can look at one quickly. Why is hell underground? The idea during medieval times was that things that were dirty, that were sinful, impure, were drawn downwards. So all of the Earthly problems would be drawn downward, with the worst being in the center of the Earth.
Incidentally, this is also why Earth was placed in the center of the universe, because this is where all the bad things are drawn, while the great things can fly up to heaven. And we even see this within the Bible with terms such as, ascending to heaven. The good goes up, the bad goes down.
But the perspective of hell in general didn’t change too much with Dante. It was more or less just codified. For instance, in the second century, we have an early Christian text called the Apocalypse of Peter. Here, we have Christ taking Peter on a tour of Heaven and Hell, and there are different sorts of torture for different sins. Before Dante, there is also a work called the Vision of Thurkill that has a lot of similarities as well. An excellent source on this is Eileen Gardner’s book, Visions of Heaven and Hell Before Dante.
So Dante was really drawing on other sources. But what he does that sticks out is the way he lays it out. He has a new detailed architecture of hell, which happens in 9 circles. He divides hell into layers, which is really based on his application of scholastic theology.
Another thing he stressed was the idea of Contrapasso, that every sinner’s crime must have an equal and fitting punishment. He wasn’t the first to think of this, but he really described the means of this.
Joseph Kameen wrote a great paper that summarizes this all up, called Darkness Visible: Dante’s Clarification of Hell. His conclusion is that Dante isn’t rewriting anything. He’s not really trying to redefine hell or create something here. Instead, he is attempting to explain hell. He wants to take an abstract concept and make it more real, so that most people could understand it. Dante takes to the vernacular to explain what hell is. He adds a bit of flair to it, but he’s really just clarifying the view. Basically, he’s seeking to be a guide like Virgil.