After nearly two centuries of Byzantine yoke, in eleven eighty five, the brothers Asen and Peter restored the Bulgarian state. In those times Yambol had been part of the Byzantine Empire. It became Bulgarian around eleven ninety four after the marches of Tsar Asen south of the Balkan Mountain. That situation continued until the middle of the thirteenth century.

After the death of Tsar Ivan Asen the Second, the Bulgarian state lost its power and the Romans gradually won back their lands to the south. That went on until thirteen and three when the Bulgarian Tsar Theodor Svetoslav conquered the fortress of Yambol and handed it over to his uncle Despot Eltimir. That was a sort of gratitude for his support during the war. For about a year the city became a part of the Kransko despotism.
But things changed very quickly in that century and the next summer, after a march of the Byzantine Emperor Michail the Ninth, Yambol fell again in his hands. At the end of the same year the armies of Theodor Svetoslav and Eltimir got the city back and once more it became part of the Kransko despotism. Then however, in the year thirteen and five, Eltimir betrayed his master and Theodor Svetoslav took Yambol away from him.
And peace did come. Yambol was mentioned again not before the year thirteen twenty two. Then after the death of the Bulgarian Tsar Georgi Terter the Second, many cities, Yambol among them, willingly adjoined Byzantium. Only a year later the new Bulgarian Tsar Michail Shishman regained those cities.

Turbulent times came for Byzantium. During the thirties of the fourteenth century, a grandfather and his grandson – Andronik the Second and Andronik the Third, were fighting for the throne. Realizing the weakness of the Romans, Michail Shishman stepped in the struggle. In the year thirteen twenty eight the Tsar camped near Diampol and he had remained outside its gates for more than two months. From there he sent a detachment of three thousand men who had to invade secretly Constantinople and to conquer it. Byzantines however were watchful and Andronik the Third launched a counter-offensive immediately. He invaded Thrace and captured Diampol once more.

Then the Bulgarian throne was ascended by the Lovech despot Ivan Alexander and he strengthened the state. Soon the new Bulgarian Tsar set off on a march to Thrace and seized many cities, and also Yambol.  After the Bulgarian armies headed back to the north of the Balkan, the Byzantines regained all strongholds, with the exception of Anhialo.

Later on in the year thirteen thirty two Ivan Alexander invaded Thrace and reached the fortress of Rusokastron. Bulgarians and Romans started negotiations and on seventeenth of July the same year they agreed that Diampol shall be returned to the Bulgarians and Anhialo – to Byzantium. On the next day Tatar Cavalry, that had been an anticipated ally, came to the camp of the Bulgarians and unexpectedly they attacked the Romans. The Tsar won and the fortress of Yambol remained within the limits of the Bulgarian state.

The year thirteen fifty one had been crucial for the whole Balkan Peninsula. New power was rising in these lands – the Ottoman Turks. Initially they captured the small town Zimpe on the Galipol Peninsula. The decades that followed were years of bloody battles and the Bulgarian cities in Thrace were the first to experience the rage of the Turks.

In the year thirteen seventy one the Christian rulers on the Balkans united against the invaders. The crucial battle was that near Chernomen where Christians suffered terrible defeat.
Thus, at the beginning of thirteen seventy three the Sultan set off on a march in order to punish Tsar Ivan Shishman for refusing to render help to the Turks at Chernomen. One of the Sultan’s armies went in the valley of Tundzha towards Kazulgaach, the present Elhovo and Dubilin, as they were calling Yambol. After capturing Elhovo in the spring of thirteen seventy three, the askers reached outside the gates of Yambol fortress. As the tradition required, first they demanded that the fortress shall surrender in order to spare the population. But the governor of Yambol refused and the town was placed in a state of heavy siege.
The stronghold fell after few months, at the height of the summer, thirteen seventy three. The hot weather spoiled the food and the water in the fortress and its brave defenders surrendered.  The Turks destroyed the fortress wall and the few surviving Bulgarians who were not sold in slavery, settled down in the neighborhood of Kargona, on the opposite bank of Tundzha.
Such was the stormy history of Yambol region in the years of the Second Bulgarian Kingdom.