" And the LORD God planted a garden eastward in Eden; and there he put the man whom he had formed.
 And out of the ground made the LORD God to grow every tree that is pleasant to the sight, and good for food; the tree of life also in the midst of the garden, and the tree of knowledge of good and evil.
 And a river went out of Eden to water the garden; and from thence it was parted, and became into four heads."
Now we come to the Garden of Eden myth, and it seems only fitting that Urbis should have a First Garden analogous to the First City. But where to locate it? Well, verse 2:8 specifically mentions "eastward", so how about placing it way east, in the Tsan Empire (the local China analogue)? It only seems fair, since the First City is an Atlantis analogue, and hence "western". This also implies that Kortus ascended to Godhood in the far East (echoing once more the Peaches of Immortality). His worship spread into the west until his eastern roots were forgotten by most, and now many faithful even see his eastern and western aspects as two different entities! A quick search of Wikipedia for Chinese deities reveals the Eight Immortals, which would fit a recurrent theme - mortals transcending and becoming deities, which (according to the backstory mentioned before) certainly fits Kortus!
As for the equivalent of the "Garden of Eden", I've had some imagery floating around in my head since reading the Dictionary of Imaginary Places (though I don't remember the exact entry which triggered this line of thought). Basically, there is a far northern province of the Tsan Empire which would ordinarily be too cold for agriculture - but four enormous warm rivers pour out of a huge central mountain (which is considered "holy" and home to numerous monasteries), cascading down waterfalls until they reach the plain, where they spread out until they fill a larger square which ultimately drains into the sea. From each of the rivers numerous irrigation channels branch out. As the water emerges from the mountain it glows and has healing properties, though this effect lessens as the water travels away from its source. Roughly speaking, the geography looks like this - with the large square representing more than 200 miles on each side:
Let's say this entire province was the Garden of Kortus, and his most valuable plants (i.e. the ones granting immortality) were growing on the slopes of the mountain. When he ascended, he cast other mortals off the mountain, though in the millenia which have passed since then various monasteries have managed to establish themselves - and Kortus does not seem to mind. A few of the Peaches of Immortality yet survive, and the monks fiercely protect their control of them. Naturally, they send a few to the Tsan Empire as tribute, which seems enough to keep hostile takeovers at bay - the mountain slopes favor the defenders, and nobody wants to risk damaging the peach trees!
" And the LORD God commanded the man, saying, Of every tree of the garden thou mayest freely eat:
 But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die."
Verse 2:17 is interesting, since we all know that's not actually what happened when Adam and Eve ate from it. Anyway, let's assume that the Tree of Knowledge survives in the Garden of Kortus as well - but as a much deeper secret than the Peaches of Immortality and whatnot, and only the most enlightened monks may eat from it, as only they can face its earth-shattering revelations and stay sane. This will not turn them into deities - Kortus presumably took that information with him when he ascended, although there are always monks who try to figure out how he did it by studying his other works..