Hi Guys!
In my opinion ConjurerDragon, your map is a fake, political product of XIX-XX century nationalism. Though I must confess I'm hungarian, but history education in my country is short of ANY national aspects, so I also have to be strict when it comes to "tales" like I'm gonna tell to you.
So I see two issues around the question and the map, I will refer to that at the end trust me
but I feel you need the know the whole story behind it, cause it's quite entertaining.
First speak about Nándorfehérvár(Lándorfehérvár till the 14th century) or Belgrade. I guess that's the issues they name the province Srbija/Szendrő, to save us (HUN/SRB) from raging about it
The city first became capital of Serbia in 1403 when Sigismund gave despot Lazarevic the fort and in its belonging land.
Sigismund von Luxemburg had PU over Hungary, Bohemia, Germany and he was the Holy Roman Emperor. But at that time (1403) he was only King of Hungary, and not by much.
When Lajos the Great died in 1382, the queen mother (Elizabeth of Bosnia) took regency over Queen Mária (older sister of Hedvig of Poland) who were promised to Sigismund (heir of Bohemia and Duke of Brandenburg). Mária in Lajos' life legally stopped being a Queen, She was referred to from then as THE KING
. You should know from the game how these things work legitimacy doubled down, and on the top of that the queen mother plotted against Sigismund and gave Mária to Loius of Anjou, Prince of Orleáns. So if you like, Loius was the first (or maybe the only one in history) who became husband of a king xDDDDD
When Hungarian nobility heard about this, they immidiately sent for Charles the Short, King of Naples.
A real race began.
Sigismund bonded his Duchy and brought as many troops as he could, and forced out a marriage in 1385 november.
On the other hand Sigismund have not yet been crowned, Mária was only 13 at the time, and Charles enjoyed extreme popularity amongst the Hungarian Estates having spent most of his life in Lajos' court. So in December when Charles arrived Sigismund fled the city. The Neapolitan King (who in fact was never called Neapolitan by anyone, it was (also) called the Kingdom of Sicily at the time) so he forced queen mother and Mária to resign, and he was proclaimed King Dec 31 1385. He sent word to Naples, his wife got word on Jan 21, and his first letters arrived on Feb 10. On Feb 18 There was a great torchlight procession in Napoli where representatives of all Italian states participated. The grand design of House Anjou came to reality, Hungary and Naples under the same crown.
Too bad Charles kept the snake queen mother close to him. On Febr 7 he became victim of an assassination. He lost an eye and got other head wounds, but miraculously remained alive. Even the assassin left the scenery, he wouldn't thought the king will live for an additional 3 weeks(!). This time he used to make last will. His 9 years old son inherits everything. After his death in few days the queen mother gave nobility and a fort to the chef, who cut the king.
Later this year followers of Charles abducted the queen mother and Mária, cutting some of the biggest supporters of the duo in the process. 6 months later, the Diet proclaimed Sigismund Hungarian King, and Mária was freed while the queen mother was killed.
So where did we start? And what does this have to do with Serbia?
Oh 1403... The 9 years old boy, whose fater was a glorified hero for days before he was betrayed. The 9 years old boy became the 26 years old King of Naples. In 1403 the pope excommunicated Sigismund and former party of Charles invited Ladislao to get the Hungarian throne due to deep unrest against Sigismund. Sigismund was in Bohemia at the time and yet another civil war broke out, this time the sides chased each other through the whole country, and in the end Sigismund won in less than year.
In that campaign he got help from Serbian Despot Stephen Lazarevic. For this help he gave him Nándorfehérvár/Belgrád till the end of his life as a fief. In 1427 the fort and all of its surroundings went back to Hungarian control. Serbians got back control of the city in 1841 but Ottoman garrison only left in 1867. Both the Brankovic and Lazarevic family had vast lands in Hungary and they were vassals of Sigismund and Albert and Hunyadi. When Serbia ceased to exist in 1439, they fled to Hungary to their friends.
Sigismund died in 1437 leaving no heir by blood, in his life he gave his legacy to Albert von Habsburg on the condition that he will continue fighting the Ottomans.
Albert led a crusade immidiately, but succumbed to disease on the road.
Hungarian nobles chose now a Polish king who was young and enthusiastic about the crusades. While Wladyslaw gathered money and strength to start something unexpected happened.
János Hunyadi were campaigning to get back something, and somehow he got successful. In 1443 winter he almost reached Edirne, and in 1444 the Ottomans were eager to make peace. Murad II knew Hunyadi was THE GENERAL of the time, and the looming aggresive expansion penalty was over his head, he didn't want war. He wanted to retire and search for religious truths while his underage son will enjoya big fat truce getting old enough to rule. So they made the Edirne peace, or in Hungarian the Várad false peace (they didn't meet). In 1444 Jun 12 Wladyslaw swore on the Holy Bible and Murad swore on the Quran, that they wouldn't break this truce.
Here's the map of the deal:
Serbia is created again (after 1439) it's the red striped area
As you can see there's a "layer" on the river Sava from Nándorfehérvár/Belgrád to Knin. It was Hunyadi's doing. Inhabitants were moved north from these areas, it was a military area, a wasteland with forts and supply lines. This area's center was Srebenik.
And you can see that there's no joint border with Wallachia. So it's definetely a no.
This peace deal wasn't alive for long, as the pope convinced Wladyslaw that his oath doesn't count. Broke truce, acted like a fool on the battlefield and whooops that's how EUIV created!
If you are curious why the Ottomans respected Serbian sovereignity despite breaking the peace deal which gave it to them tell me that's an interesting story too!
