In the Greyhawk setting as presented in the 24 DMs Guide:
In the Old Keoland region of the subcontinent Flanaess, the mountainrange Jotens is an excellent place of origin of the Goliath species. It swaths the northern border of Yeomanry. An elected Goliath governs Yeomanry. All of the Giant species are nearby across the western mountainranges Crystalmist and Hellfurnaces, and the coastlands of Jeklea Bay. The name "Jotens" appears to derive from Norse Jötunn that includes every kind of Giant.
During this era of Greyhawk, the subcontinent Flannaess suffers escalating attacks from Tiamat. Her Chromatic Dragons and the Metallic Dragons who combat them are everywhere. Typically these Dragons are territorial solitary creatures with vast fly zones, but they gather in councils and for war. The Chromatics especially assault remote poorly defended Humanoid communities, to expand their territories. The western mountainranges Crystalmist and Hellfurnaces are known for their highly aggressive Chromatics. The order of the Watch builds fortresses across there to defend the nearby Humanoid communities. Even near the dense populations around Greyhawk City, various species of Dragon are active across the lands southeast, from Mistmarsh thru Bright Desert. Somewhere around Bright Desert suits a place of origin for the Dragonborn species as a diversely ancestral draconic community. Additionally Dragons soar frequently across Northern Flanaess. A norsesque Dragonborn community is appropriate in the North Kingdoms, such as Frost, and near waterways.
(My Greyhawk will make these regional North Dragonborn feature the colors of Black, Silver and Brass, and exhibit the Linnorm legless serpentine form, slithering upright with arms. These are born resembling snakes, developing arms when Wyrmling (playable level 1), only some later develop wings as Adults, and Ancients can reach Gargantuan sizes. These Dragonborn mature magically (optionally while leveling), and shed skin to reveal an emergent form. Moreover, individual Dragonborn can be born anywhere from an egg that a Dragon parent enchants.)
Normally, Tiefling lack a native culture, being whatever Humanoid culture they are born into. However the Cambion Iuz rules his namesake land that teems with Fiends. There are Tiefling here participating in the Fiendish cultures of their respective lineages.
The native cultures of each species are of interest. But typically these species are today citizens of the many diversely Humanoid communities.
Notably, Dwarves are prominent are in Mistmarsh near Greyhawk City, Hestmark Peaks near Sunndi, and especially the mountainranges of Old Keoland. A dwarven princess rules the principality of Ulek and commands a powerful navy. Gnomes are prominent in the highlands near Greyhawk City and of Hestmark Peaks near Sunndi, as well as the forests of Celene and mountains of Lortmil that divide Central Flanaess and Old Keoland. Gnomes are one of the founding species of the Valley of the Mage magocratic culture (the others being High Elf and Human). Halflings are prominent in Grandwood Forest near Sunndi and Lortil Mountains.
Of course, the traderoutes across Flanaess have long ago intermingled the Humanoid species. But even the brief setting descriptions of Greyhawk highlight locations where native cultures prevail, even for Goliath of the mountainrange Jotens and multispecies Yeomanry. Only the Dragonborn seem to need explicit locales for native cultures.
