"The last glints of the sun shone on the golden banner of Nemedia with the scarlet dragon, unfurled in the breeze above the pavillion of King Tarascus on an eminence near the eastern cliffs." -- Robert E. Howard: "Hour of the Dragon"
Second most powerful of the Hyborian kingdoms, it lies east of Aquilonia, south of the Border Kingdom, west of Brythunia, and north of Corinthia and Ophir. The Border Range lies between Aquilonia and Nemedia. Most of the passes into Aquilonia were in the northwest; two southern passes existed, one was a well-defended gap in the range that the Road of Kings ran through, the other was the difficult Pass of Oteron, which Conan once used. At the south end of the range lies the Tybor Gap, a large river valley that connects the kingdoms of Aquilonia, Nemedia, and Ophir. The rugged, impenetrable range of the Karpash Mountains lay on the southern border with Ophir.
The capital city, Belverus, lay in the western part of the kingdom on the main road to Aquilonia. This highway, the Road of Kings, continued eastward to the vicinity of the eastern Nemedian border, then dropped into Corinthia and eventually crossed Zamora and the Eastern Desert.
East and west of Belverus were rich croplands and orchards. Northwestern baronies protect the borderlands between the Border Kingdoms and Nemedia proper as far as the Great Salt Marsh. The north-flowing Yellow River marked the heavily forested eastern border between Nemedia and Brythunia, emptying into the Salt Marsh. Two other rivers, the Rhyl and the Urlaub drained interior Nemedia, since without them the country would have been a virtual desert and not at all like the land described in the Saga. Most of the Nemedian rivers have basin-style drainage into the Salt Marsh.
Nemedia was anciently a part of Acheron. People of the Nemedian hills boasted of their Acheronian blood. Invading Hybori destroyed Acheron, and it seems likely that Nemedia became the first of the Hyborian kingdoms. The elephant-being from Yag mentions it first among the new Hyborian nations.
Nemedia waged intermittent war with Aquilonia for centuries, but its western neighbor never made much headway against it. Its emblem was a scarlet dragon. Nemedia had a long tradition of scholarship, perhaps an Acheronian heritage. The Nemedian Chronicles have told most of the history of the Hyborian Age, including the Saga of Conan.
In the turbulent years following Conan's reign, Nemedia was defended by mercenary Aesir, who successfully withstood several waves of invaders. It later became a Nordic kingdom before being overrun by the Cimmerians and other tribes fleeing the advancing glaciers.
References: Hyborian Age I-II, Tower of the Elephant, God in the Bowl, Queen of the Black Coast, Hour of the Dragon, Conan the Great, et al.