This one took me by surprise, though it probably shouldn't have since it's become such a turning point in the MCU.
In Avengers: Age of Ultron (May 2015), we're introduced to an Eastern European country called Sokovia. Sokovia is a major part of the story as that's where Baron Strucker's base is, that's where Scarlet Witch and Quicksilver live, and that's where Ultron decides to attack. It continues to be important in Captain America: Civil War (May 2016), because it's where Zemo's from and it's (obviously) a large part of the reason behind the Sokovia Accords.
Here's the weird part: I'm not entirely sure why they created Sokovia for the movie. In the comics, Scarlet Witch and Quicksilver are from the Eastern European country Transia, and that would've worked just as well.
Regardless, Sokovia is here, and it makes sense that the comics would eventually use it, which they did in Captain America: Steve Rogers #5 (September 2016):
Sokovia also appears in issue 7. Whether it'll become a staple of the Marvel Universe like Wakanda or Madripoor remains to be seen.