So for those who don't know, Human Ryze has been renamed to Young Ryze and is pretty much his canonical appearance as a young man (or close to it). What's interesting though is that his clothes and skin tone, which to me seems a tad darker than many other human champions, indicates he's potentially Shuriman. Couple this with the desert and Shuriman themed architecture in Young Ryze's splash art and I'm led to believe that Ryze was Shuriman born or visited ancient Shurima in his early days, keeping in mind that he's now centuries old.
You can't look at that building behind the magic around Ryze's hand and tell me it doesn't look like the Palace of Ten Thousand Pillars (The building with the Sun Disc above it).
I mean we'll probably get solid information with his new lore, but hey, I saw something interesting and wanted to play detective, so sue me.
EDIT: Reav3 has confirmed that Ryze isn't Shuriman, and really doesn't belong to any one nation, but he has been to Shurima as the splash art suggests.