Czar Ivan Strashimir's state spanned the lands between the Timok and the Iskar. He was crowned Tsar in Vidin at the request of his father Ivan Alexander. During his lifetime he had attempted to settle the relationship between his two sons from different marriages by making the elder one ruler of the northwestern Bulgarian lands. However, distrust and resentment persisted. In times of ordeal, Ivan Sratsimir and Ivan Shishman failed to come to agreement, making things easier for the conqueror.
Ivan Strasimir has been the subject of much debate by historians. Was he an able or a mediocre ruler? Either way, however, the tiny kingdom would have been too frail an obstacle to the advancement of Sultan Murad and his successor Bayazid. In the spring of 1365 the Hungarian king Ludovik overran the tiny kingdom and incorporated it into his state, taking the Bulgarian ruler captive. Ivan Sratsimir was imprisoned in Croatia and forced to convert to Catholicism. Several years later Ivan Alexander, assisted by Vlach troops, restored his son to the throne. After his father's death in 1395, Ivan Sratsimir became a Tsar in his own right.
In the two decades that followed there is no evidence in the chronicles of successful military campaigns against the Turks. Conscious of the weakness of his army, in 1388 Ivan Sratsimir declared himself vassal to Sultan Murad and allowed the Turks to enter the fortress of Vidin. His aim was to guard his throne and save his subjects from death at the hands of the Turks. For a while he even took Sofia away from the Turnovo kingdom in the hope that, of the three fragments of the Bulgarian state, his would survive. His hopes were soon dashed. The wave of Turkish invasion menacingly approached the borders of his small kingdom. At the beginning of 1396, the Western European rulers finally realized that the Ottoman hordes were a threat to them too and with the Pope's blessing the Hungarian King Sigismund led a crusade against the Turks. The knights headed southeast, to the Balkans, filling Ivan Sratsimir with hope. He renounced his vassal status, slaughtered the Turkish soldiers in the Vidin fortress and joined the crusaders. However, the European army was disunited, each commander seeking personal fame and achievement. On the 25 th of September 1396 the Turks routed the European army at Nikopol. Vidin fell, too. Bulgaria's last medieval ruler was taken captive and died in Asia Minor. Bulgaria fell under five centuries of Ottoman rule.
The Ottomans went on to besiege and almost take Vienna. The Ottoman empire became one of the most powerful empires in the world. At its height the empire included most of southeastern Europe to the gates of Vienna, including modern Hungary, Serbia, Bosnia, Romania, Greece, and Ukraine; Iraq, Syria, Israel, and Egypt; North Africa as far west as Algeria; and most of the Arabian Peninsula. The term Ottoman is a dynastic appellation derived from Osman {Arabic: 'Uthman}, the nomadic Turkmen chief who founded both the dynasty and the empire.
As the Ottoman empire devoured Byzantine, it's scholars fled west. Ancient Greek literature as still survives, including that of all the historians, was preserved by the Byzantine scholars. When, around the year 1400, the teaching of Greek was introduced into Italian universities by Byzantine scholars, they brought also their superior techniques of literary scholarship, transforming thereby the study of Latin authors as well as introducing into western Europe the treasures of Greek literature. One result was the emergence of the new Renaissance historiography.
In the 7 centuries preceding the Ottoman conquest, the descendants of Khan Asparuh had managed to forge a nation on the most contended land on the European continent. Against all odds, on the crossroads of Europe, Asia and Africa, despite invasions, wars, migrations of peoples, empires, and the danger of religious and cultural conquest - Thracians, Slavs and Bulgars were forged into one nation. One nation with it's own language, alphabet and church. And that is why the Bulgarian nation survived the Ottoman empire.
