Prim is a Czech company, established in 1949, that was a major supplier of watches in the Comecon (the communist counterpart to the EU during the Cold War and one of the reasons that the economies of the East were so screwed up, but that is another post for another time and a different place...), especially higher-end military and dress watches. While nowhere near the volume of production that Poljot or Ruhla had, they were considered to be quite good, with their own high-quality movements that were generally superior to the Ruhla (East German) and the equal of the better (usually older) Poljot movements.
Probably best known for military issue watches (Czech Air Force) and sport watches, as well as some high-end gold dress watches for the upper levels of Party nomenklatura.
They survived the collapse of the old Czechoslovakia economy - barely - and continue in existence today. They make a series of watches today, with their own movements, but face two major challenges: volume and price. Their prices are premium, but enjoy only limited sales outside of the Czech Republic and Slovakia, where they remain, due to local patriotism, fairly popular as a domestic-made upper-end watch. For those outside of Czech Republic, the prices are simply too high (at least in my opinion) for them to be serious competitors. They have also apparently largely exhausted their reserve of watch movements and have apparently moved to making largely watches with ETA and Ronda movements in order to remain competitive, although I think they continue to offer several in-house movements (cal. 94 and cal. 98). Employment is down to around 50 people, from several hundred. Their website is here. Here is a nice collection of pictures from a visit to their factory as well.
Take a look at their collection of sport watches, and you can see where I have my problems with their prices: for a Igen 38 with the hand-wound cal. 94, they want €1939! That's for a watch with a moderately finished movement: I can get, for that price, significantly nicer-finished watches in both Germany and Switzerland (from Sinn, Stowa, Guinand and any of the major Swiss manufacturers). I could see acquiring one - I've got Czech ancestry - for half that price, but not that price...
I've got several Prims, but the most highly-sought after vintage watches are their sport watches (especially their divers) and military-issued watches. Not many of those survived over the decades without "disappearing".