As you'll likely be aware already @aulyre, there's a vast and still-growing literature on the archaeo-historical aspects of the region, and you could easily spend years simply wading through as much of that as you'd care to - I have, certainly, starting back in the 1990s!

Of my own maps of this region, I posted a selection just over a year ago on the Forum here. Unfortunately, this was shortly before the Forum underwent a major revamp to its current incarnation, so the post now looks rather a mess, as we had to embed images rather differently then, using an "[Image_12345]" coding notation, but the images are all still there, just no longer where they were meant to be in relation to the text, so you have to hop up and down to get the full gist properly.

As for references, a couple of atlases I found extremely helpful when I was starting out might be of interest, if you haven't come across them yourself as yet, and a couple of texts.

• Michael Roaf's Cultural Atlas of Mesopotamia and the Ancient Near East (published in 1990), which I was thrilled to discover on checking this evening is NOW FREELY AVAILABLE TO DOWNLOAD COMPLETE (!!!), and with a string of appended corrections, thanks to the kind offices of its author, via the Academia website, as of 2017! Link. I think you will need a (free to join) Academia membership to download the full PDF, but that isn't too onerous. For all its date, it is an astonishingly inspirational work in my opinion.
• The Barrington Atlas of the Greek and Roman World edited by Richard Talbert (2000), which unfortunately isn't available online yet, though it is available for iPad as a download (as of 2013). Otherwise, the hardback version is available to purchase alternatively, which I think still comes with an additional CD-ROM, according to some comments I found online (the library copy I borrowed more than a decade ago had one), including this Wikipedia page, although some of the links from that are now broken. GBP prices (brace yourself!) for the hardback start at about 265 GBP (Amazon UK lists), but the iPad version is a less fearsome circa 15 GBP instead (albeit you'll also need an iPad, so swings and roundabouts...). The Princeton University Press pages for these are here: hardback version -- iPad version. The related Ancient World Mapping Centre website is probably worth a visit as well, albeit they've been having major site issues this year, so a number of links don't work currently. Most of their Free Map pages are still functioning, however, and are certainly worth a look too. The Atlas is another astonishing work, if for a somewhat later period than Roaf's text.
• Civilizations of the Ancient Near East edited by Jack Sasson (1995) is a monumental four-volume collection of specialist essays on all manner of topics for the region. The length and quality of individual contributions can be variable at times, but it is a wonderful means to find out at least some basics on a vast array of topics, with follow-up references to help get you started looking for more. Irritatingly, I can't even find an online description or a complete review of it, though I suspect barring extreme good fortune, it will mean accessing a library copy now anyway.
• Ancient Iraq by Georges Roux (1993) is probably THE classic single-volume introductory text to the region and period. It is, incredibly, and despite its date, still currently in print! You can also find it available to borrow or purchase via the Internet Archive here (limited preview version otherwise).

This has taken a lot longer than I'd expected to compile today, so I won't try to say more; there's enough to be going on with already, I suspect in this little lot!

It's certainly a very beautiful map, and I know well how difficult it is to find a suitable real-world base map from which to draw this region, so I think you've done a splendid job with it!

As Sue said, the seas look a little "double-exposed" currently though.

How historically-accurate were you intending to be with it?

I ask, as ancient Mesopotamia is a particular place of interest for me, especially around the 3rd-2nd millennia BCE, along with the Black Sea and places adjacent around the 2nd-early 1st millennia BCE, and east to what is now Afghanistan, Pakistan and western India. They're places I've mapped and studied in some detail previously, and there are points I could make which might be of use, though only if you were wanting it to be more historical.

The river lines are very complex, particularly if you're going for that historical route, and a specific time-frame. The Tigris has pretty much held its course over the millennia, largely thanks to a stonier bed, but the Euphrates has drifted hither and yon across the silts of southern Mesopotamia especially, encouraged by deliberately-dug irrigation canals in places, beginning around the later 4th millennium BCE, for instance.

I know when I started out trying to map parts of this region, something that surprised me was how poorly different published atlas maps compared with one another as regards the modern watercourses, especially for anything other than the major river channels, even in the specialist (i.e. archaeological-historical) literature.

Looking a lot better now!

Yes, I think the walls would work very nicely for ruins too.

If the stepped outer surface was full regulated, it would also work for buildings such as ancient Mesopotamian temples, which had deliberately constructed outside walls that had this kind of "vertical recesses" patterning all round them. I've had to draw these before, both by hand and on computer, and it can be pretty tedious for a larger building plan!

There is an old text-file of the fonts available via a standard Win 10 installation plus those fonts that come with CC3+ and its numerous add-ons and in the Annuals, which is intended for use by Atlas map creators, although it hasn't been updated for some time (and I did run into a problem because of a duplicate font name for the "Mayan" font that came in the 2019 Annual, which I already had installed; so the list won't be infallible under such circumstances for others). The text file is available via this post from March 2018.

I have to admit, I now tend to list whatever fonts I've used in my Atlas maps as part of the Submission document for Remy, which makes it easier to spot if there could be a problem (I hope!). Plus it also serves as a reminder to me to check that text file to see what fonts are preferable to use.

You might want to add a box and maybe a background to the map key here, and move or delete that "50" fathom depth label currently in the key. It looks a little odd to have the green low tide line marker set between the 75 and 50 fathom contours presently, for instance. Might be worth adding a land indicator to the key as well? And perhaps a compass pointer.