The show is sloppy with the lore. The only hint of a prewar faction other than America is the crashed USSR satellite. Which kinda implies a Russian role in the conflict leading to the Great War (it was the US vs China).

The prewar conflict is retconned to be a Cold War Communism vs Capitalism situation, when the war was spurred by global resource shortages and inflation.

There's no hint of organized civilization in an area previously occupied by a state so large that it was building railroads, manufacturing concrete and weapons, and expanding East.

Not that they can't retcon some stuff in Season 2, but they did say that every faction will think they "won New Vegas." That could mean many different things, but given how devastated all the factions you don't side with after NV are, none of them seem like particularly well-considered decisions to me.

I enjoyed the world that Fallout built on the West Coast, which was at that point just a modern society. The show scrapped it to present a total wasteland, when there are so many new settings already alluded to in the lore.