The FAQ has a bunch of stuff on this. The sections "Late Antiquity and 'the Dark Ages'" is I think where you want to look, but some of the other sections under the Late Antiquity heading will also have good posts.

The question you raise, if Rome fell or transitioned into something else, isn't settled. There are scholars that see a strong break in the 5th century CE, and scholars that see continuity. The traditional position is a strong break in 476 or so with the end of the Roman empire in the West, most recently expounded to my knowledge by Heather and Ward-Perkins. The continuity people follow Peter Brown, who literally invented the idea of "Late Antiquity" instead of "The Dark Ages." Brown's idea is that society transitioned into a medieval form without meaningful disruption. I wrote about all three of these guys briefly here.

There's lots to say about all of this, especially because it's not a settled question at the moment, but I think that can give you a start.

Thanks for clearing things up. But didn’t the Eastern side have more of a Middle Eastern or Turkish culture which kind of led them to become different than Romans?