Gedberst is a pretty traditional DnD world in terms of nations being mostly racially homogenous. Though there are typically dwarves living just about everywhere, and Orcs and Half Orcs are increasingly common after the long winter, Humans are typically distrusted by other peoples, and elves tend to keep to themselves, with only a very few Wood Elven nomads living outside of the Wode. As such, the different DnD races tend to have very distinct cultures.
Humans
The first humans in gedberst arrived from a continent far to the east, they were a large contingent who had been banished after an ancient war, when they landed at the very east of gedberst, they quickly moved across the land up to the Krigsberd Mountains. They lived for a long time under the rule of The Titan, who ruled the entire continent. Ten thousand years ago, after The Titan and his army were defeated in battle by the Dragons' Coalition, ambitious humans, descended from the captains of their ancient ships formed kingdoms around a central mountain they called Raven's Peak. The kingdoms around Raven's Peak fought for a while, but eventually came together and formed The Republic, which was composed of the human Kingdoms around Ravens' Peak.
During the years of the republic, revolutionaries and other dissonants were banished over the mountains along the western borders of the kingdom. That land was generally lawless, and ungoverned for a long time. To the west of the mountains, some settlers (who left willingly, seeking new lands and prospects) arrived in the large plains and forests between the Krigsberd Mountains and the Starfall pass. Until the collapse of the dwarven empire these people lived as a client state with limited rights and powers. After the collapse, the nation of Gardmark was founded, with its royal line living on the northern coast.
The humans of Gedberst are generally working folk, known more for trading prowess than any great armies or craftsmen. Their Nations have become increasingly powerful over the course of the Age of Dragons, and Renewed Age of Dragons. The most notable historical event focused around humans was the Lich war, in which human scholars from the republic college sought power and immortality, turned to evil, and brought armies of undead against the people of gedberst (and the world as a whole).
Dragonborn
Dragonborn are a small population who are closely allied with the king of Rekdomark, and have been allied with humans in the east for a very long time. Very little is known about the dragonborn's own culture. The only dragonborn who are regularly seen are the Dragon Knights of The Republic, who are honor-bound madmen, driven only by fanatic loyalty to the King of Rekdomark. Dragons are known to kill dragonborn whenever possible, perhaps out of jealousy for the dragonborn mimmicking their form.
Dwarves
Dwarves were created along with the earth by Morid, and serve as the protectors and keepers of the earth. Morid's religion is one of craftsmanship, and focuses creation as the greatest service to Morid. The other prominent dwarven god is the Oath Lord, who's true name is kept a great secret by his priests. The Oath Lord was supposedly the first Dwarf to forge an Oath Ring, and was elevated to godhood for his using Oath Rings to keep the peace in his homeland (a place very different to the Dwarves of Gedberst). Dwarves held great power over Gedberst in an earlier time, but are now divided and weak, after the dissapearance of their leader Kad'Zur.
Giants
Dwarves are like lobsters, and do not stop growing larger as they age. When a dwarf can survive for a great and long life, they will become a giant, and gain great magical power. The Giants used to rule Gedberst under the leadership of the Titan, but were overthrown by the Dragons' Coalition. Nowadays, few of the old giants are left, and few dwarves live long enough to become new giants. As a result, giants are increasingly rare.
Orcs
Orcs used to be pretty much limited to the north in terms of where they lived. During the Long Winter they were displaced by a Gnoll invasion, and were forced south. This resulted in a large war across the whole continent. Orcs have a tradition that in the winters (which are often harsh, and limit the resources of a tribe severely) they will fight ceremonial wars among themselves. During the long winter, the "last snow of winter" did not come for ten years, and so they continued to fight out of religious obligation the whole time. This stressed both their own population, and that of all other people in Gedberst.
Half Orcs
Half Orcs are relatively new and uncommon. The royal line of Krigsberd are Half Orcs, descended from a human warrior who won control of a large Orc tribe through combat, and was able to ally all the Orcs in Krigsbert into a single nation, which worked alongside a new human government. Generally half orcs are unheard of outside of Krigsberd.