Tsar Constantine II Asen

Constantine II Asen, also known as Constantine Sratsimir, was the son of Tsar Ivan Sratsimir and Tsarina Anna, daughter of the Wallachian prince Nicholas I Alexander. There is no clear information as to whether Constantine II received the title of tsar, and he is traditionally considered not to have ruled the Vidin Tsardom.

In 1365, after the Hungarian king Louis captured Vidin, he sent Tsar Sratsimir and his entire family to the Croatian fortress of Humnik, where they were held captive for four years. In 1369, Sratsimir and Constantine were released, but Constantine's sister Dorothea remained with the Hungarian queen Elizabeth Kotromanić and married her cousin Tvrtko I Kotromanić.

As heir to the throne, Constantine took part in a mission to the Ottomans in 1394 together with Metropolitan Joasaph of Bdin. In 1404, he and Fruzhin, the son of Ivan Shishman, began a revolt against the Turks known as the Uprising of Constantine and Fruzhin. Despite its initial successes, the Ottomans under Musa Kesedzhi defeated the uprising in 1413. Constantine II was driven into Hungary, where he spent the remaining years of his life. He died on 17 September 1422 in Belgrade and was buried in the Church of St Petka in that city.

There are different interpretations of the fate of the Vidin Tsardom after 1396, but most historians consider that it fell under Ottoman rule during this period.