There was a specific type of armor panoply that the Byzantines used called "Klibanion" or "Klivanion" (κλιβάνιον), which consisted of lamellar over mail with some other plates or strips of iron (very loosely analogous to what Gary Gygax used to call 'split mail') on some of the limbs.
This was considered effective but heavy and was mainly worn by Clibanari / Cataphract heavy-cavalry. The Byzantine Anna Comnena describes a Byzantine noble being hit with a full lance charge which knocked him half out of his saddle, but being unharmed due to his klibanion. The word seems to be linked to the name for cavalry - so it means something like 'armor of the oven men'.
https://en.wikipedia.org/wiki/Klivanion
The Swedish Varangians and Rus / Russians seem to have adopted this at least some of the time, though it's unclear how popular it really was.
By the High Middle Ages in Rus city-states you start to see indications of something which looks similar but is a bit different - mail armor with small iron or steel plates linked into the mail itself. This seems to be unique to the Rus areas (Russia, Ukraine, Belarus etc.) and into Central Asia as you don't really see it in other parts of Europe. This armor is sometimes called 'Bakhterets' or ''Yushman' but is also known by many other terms, in Rus lands and also in Persia, India, Turkey etc.
There are some threads on this type of armor in Myarmoury which is probably your best open-to-the-public source.
https://myarmoury.com/talk/viewtopic.php?t=7075
This is a re-enactor wearing some
And this is some antique armor of that type. It's pretty cool looking and probably a bit better protection against arrows than just regular mail, but not nearly as heavy as all the layers of Klibanion.
These are Russian:
I think this one is Persian or South Asian
This is a full panoply, I think Russian
Closeup of armor
Spoiler: Yushman closeup
Some Russian artists from the 19th and early 20th Century made very accurate depictions of this type of armor, for example many by Viktor Vasnetsov as you can see here:
Spoiler: Vasnetsov
Those guys in the paintings, incidentally, are Bogatyr, a special type of Rus knight-errant of whom there was quite a rich body of literature, mainly from Veliky Novgorod, one of the great Rus city-states - arguably the greatest in the medieval period, though eclipsed by Muscovy in the late 15th Century.
https://en.wikipedia.org/wiki/Bogatyr
You can go into a really fun rabbit-hole reading about those dudes. Great RPG story-hook fodder.
G