[Rolando]

I doubt most orcs or reptiles would venture deep into the djin lands, as both tend to be superstitious and may fear strong magic.

Even then only djins near the edge of the orc lands and great desert get to worry about them. I can see the northern djini having a lot of orc slaves or even guards, also use them for magical experiments and sacrifices... I can see the orcs as victims for a change in an adventure, maybe with some lizardfolk as allies to twist the monsters theme.

I also see the castles and palaces of the djins as magical wonders, with magical weather and impossible architecture. Surrounded by other wonders and defenses.

The lands between are low mana, most of them, but there may be lots of magical creatures, creations and natural phenomena due to the djins interventions and "games" to fend of boredom. Many tribes of different races in a kind of post apocalyptic setting. With wastelands/savage-lands surrounding wondrous cities, from those cities sometimes soldiers in magical armor come to raid the tribes or settlements... somewhat like Zardos but with lots of magic and the Wizard is really a powerful wizard.