Kind of depends on what you’re interested in. They’ve been making wine there for centuries.
Back in the 1800s the Lecanda family planted some Cab, Merlot, Malbec, etc. They planted along the Duero River and made some decent wine. That became Vega Sicilia. But the wine wasn’t really known, it was consumed by them and by friends and nobody else was really working there. Mostly there was just a lot of rustic, rough wine made. In the 1920s a group of growers got together to form Protos. Franco liked co-ops and in RdD as elsehwere, there were a lot of co-ops that turned out rustic wine.
It was only in the 1970s that Alejandro Fernandez was one of the first after the Lecanda family to try making serious wines. He founded Pesquera and he worked with a few others to create the D.O., which was established only in 1982. There were only nine wineries at the time. Protos at that time had two brands - Bodegas Peñafiel and Ribera del Duero. They gave the latter name to be used as the DO. They’re still making wine and are worth a visit if you’re ever there.
Fernandez got his wine into Parker’s hands. Of course, at the time, Parker had pretty much zero experience with Spanish wine other than a passing idea of Rioja, so he was amazed and scored them highly. Since that time interest in the area has exploded.
The area is pretty narrow as it follows the river, but it’s at a fairly high elevation and is the highest elevation in Spain as far as I know, and fairly high period.
At one point people outside of Spain were saying that there’s no “terroir”, one British writer in particular, but that’s shifted dramatically more recently, and now there’s some enthusiasm for the idea of classifying subregions based on it. You can distinguish regions by taste sometimes, but most people can’t and I wouldn’t focus on it. In Burgos for example, there are a lot of really small plots that have belonged to families for centuries. The land is useless for about anything else, so it was used for vines. Some plots are over a century old. The wines tend to be tannic and ripe and chewy, and for me, that’s the source of the best wines, but really the winemaker is more important. It’s kind of like Bordeaux in that sense.
But not all. The iconic producer is of course Fernandez, who passed recently. But the producer to note is Mariano Garcia. He has been making wine there since 1968, initially with Vega Sicilia for decades until a falling out. Now he and his sons make wines under their own names.
Pesquera tends to be a little funky and instantly recognizable. It has what I call “Tempranillo funk”, which is characteristic of the grape and pronounced in that wine. There are several wineries under the umbrella but the other in Ribera is Condado de Haza, which has a little less of the funk but is often quite enjoyable. Neither is particularly tannic or uber ripe.
Emilio Moro is another one that’s been around for a while, dating back to 1932. But they’re different. They abandoned the crianza/reserva/GR classifications and just make the wine they think makes sense. They favor a big style that’s not elaborately oaked, but has definite oak notes.
Perez Pascuas was one of the first founded under the new DO name. Again, not big, just easy to drink.
Then of course, you had to get someone trying to be bigger and blacker and riper and along came Peter Sisseck who made Pingus. He had shown up to manage a new project called Hacienda Monasterio, and you should try their wines. For his pet project, he decided on 200% new oak (!) by using 100% new for a year and then dumping those barrels into new barrels for another year. I may be off on the time - don’t know if it was one year, two years, whatever. His first vintage was 1995, which was an outstanding year in the region. It got to Parker at the en primeur tastings in Bordeaux and he gave it 96-100 and called it one of the best young wines he had ever tasted. So his love affair with Spain began. Bob was at his height at the time and the wine overnight became one of the most expensive wines in Spain.
When the container bringing it to the US was almost entirely lost at sea, it made the wine a sensation. Sisseck has since really backed off on the oak and the wine is much better.
Garmón is the latest project of Mariano García and it reflects the evolution of his sons. It’s backed off somewhat from the oak and size and is a more refined wine than some. You may as well try Aalto, Astrales, and Mauro too. All good, some may still be on the oaky side but recent vintages have backed off a lot.
Félix Callejo is another producer worth trying. They tend to favor acidity over power. Pago de Los Capellanes tends to be a higher-alcohol wine but it’s always balanced. Torres does a wine called Celeste that’s a good intro to the region. It’s not a vineyard-specific wine but it’s a good overview of what you’ll get and it’s really cheap.
One of my favorites is one I used to sell called Casajus - tannic, structured, made to age, the wines are just magnificent and as good as anything coming out of the area IMO. Bodegas Navarro Balbás is hit or miss and for some reason also hit or miss with importers. Abadía de Acón can be very good with definite notes of chocolate.
I would probably look for producers rather than area, since there’s so much flux and development as people are refining their styles.
And it’s a red-wine region. The allowed white grape is Albillo, but that’s only made for local consumption, although some may find its way into the rosados.