All races can, to some extent, be found across the Two Continents. There are a couple that are most common in certain contexts, though:
When people think of Half-elves, they think of Erynian Ambassadors, and when people think of Gnomes, they often think of Gnome merchant caravans. That is not to say those races do not exist outside of that context, merely that they are famous for those contexts.
Kingdom of Andor
Makeup: Human
Trade: Dhimtorhm, Hypatia, occasionally Briven
Political Situation: On-again/off-again war with Briven Empire across the Strait of Carden
Noteworthy: Equestrian society, major lumber exporter
Briven Empire
Makeup: Reptilian races;
Dragonborn in the northern desert, lizardfolk in the greener South
Trade: Erynia, Dar Garuhm, occasionally Andor
Political Situation: On-again/off-again war with Andor across the Strait of Carden
Noteworthy: “Gold basket” of the Twin Continents
Dar Garuhm
Makeup: Dwarven
Trade: Briven, Sea trade on Caranian Sea
Political Situation: Neutral
Noteworthy: Major international banking site
Dhimtorhm
Makeup: Dwarven and Gnome
Trade: Andor, Hypatia, the Underdark
Political Situation: Isolationist outside the mountains, clan politics inside them
Noteworthy: Primary trade route with the Underdark, neutral buffer between Andor and Hypatia
Kingdom of Hypatia Makeup: Mixed
Trade: All
Political Situation: Legal disputes over ownership of mixed above/below ground cities with Dhimtorhm threaten traditional surface divide
Noteworthy: Merchant kingdom, Naval power
Erynia Makeup: Elven
Trade: Hypatia, Small trade with Briven, Ista serves as Elven goods outlet
Political Situation: threatened by Aecherran raiding and Hypatian logging
Noteworthy: historically owned much more land, wars with Briven Empire, wars with Aecherran Dynasty, and Hypatian logging reduced the Erynian Forest to its current size
Aecherran Dynasty
Makeup: Orcs, goblinoids
Trade: small trade with Hypatia and Thogdurral
Political Situation: Aggressively expansionist but blocked by mountain ranges and a lack of naval power
Noteworthy: Repeatedly, raiding expeditions have stretched too far and been cut off from returning, resulting in roving warbands that occasionally settle in other nations. Some civilize. Most do not.
Thogdurral
Makeup: Dwarven, some gnome
Trade: Kaston Republic, Hypatia, Cautious trade with Aecherran Dynasty via border forts
Political Situation: Stalwart Defenders, seagoing trade threatened by Crossquay pirates and aquatic monsters
Noteworthy: Considered the most militarily advanced nation, home to airships
Kharak Zul Makeup: Dwarven/gnome
Trade: Mercenary bands
Political Situation: Independent City-State
Noteworthy: Originally formed by Dhimtorhm outcasts
Kaston Republic
Makeup: Gnome
Trade: Hypatia, Thogdurral, Dhimtorhm, caravans
Political Situation: Threatened by Crossquay pirates, monsters of the Northern Wastes
Noteworthy: Origin and home of most of the Gnome caravans travelling the Two Continents
Crossquay
Makeup: Menagerie
Trade: Piracy
Political Situation: Loose collection of loosely regulated city-states, threatened by monsters of the Eastern Ocean and Farthest Deeps, and by naval patrols
Noteworthy: Originally the naval center of the Ruathan Empire
Caranian Sea
Aka the Inland Sea
A naval passage between the Western Ocean and the Ruathan Sea via the Strait of Carden and Hadrian’s Canal, the Caranian Sea is relatively shallow and strangely free of monsters. This makes it an area of safety for sea trade – so long as your dues are paid.
Fax Island
Aka Fax’s Folly
An island few have survived approaching and fewer have landed upon, not much is known about it. What is known is that almost nothing grows there.