In my book series, the Aurean Empire is a vast entity spanning an entire planet. I'm kind of wondering what parts of my empire would the Aureans draw their best soldiers from (for example, the Roman Empire generally got their best recruits from the Balkans, the Byzantines got their best soldiers from Anatolia, many of the British Empire's best troops were from Scotland, etc). Which types of physical geography produce the best soldiers?
For some context, the tech level we're talking about is Late medieval/very early renaissance (cannons but no arquebuses yet). Here is each relevant region of Aurea and what areas of the real world their physical geography and climate best compares to:
Calissylvania: Brazilian Cerrado
Gregoras: Southern Appalachia
Sparteia: South Florida in the north, San Gabriel Mountains in the south and interior, Yucatan in the northeast
Monsaltu: Mexican Riviera along the coast, San Gabriel Mountains in the interior
Taurope: Southern California without the desert
Cularo: West coast of Turkey
Lycian Desert: Arabian Desert
Pagomenos: Colorado Plateau, specifically the wetter parts near Flagstaff, Arizona
Argentolian Desert: Sonoran Desert with the Floodplains of Mesopotamia
Pheron Valley: Mojave Desert with the Floodplains of Mesopotamia and a huge freshwater lake the size of Lake Ontario
Nikos: Outer Banks of North Carolina along the coast, Cascadia in the mountains, Great Basin Desert in the far north
Imbreus: French Riviera along the coast, Sierra Nevada in the mountains
Nypros: Northern and Central France
Lurias: Northern and Central France along the coast, Gobi Desert in the interior