A city in the northwest corner of Bulgaria, near the Serbian border. In the middle of the 13th century, the area near Vidin separated from the rest of the weakening Bulgarian kingdom. At the time of the Kosovo battle it is the capital of an independent Bulgarian principality, tributary to the Ottoman empire. The usual spelling is "Vidin", which is how it appears in the Serbian text. I don't know why it is changed to "Vidni" in the English translation; that may be a typographical error. Zvechan

Vidin is a town on the southern bank of the Danube in northwestern Bulgaria. It is close to the borders with Serbia and Romania, and is also the administrative centre of Vidin Province.