to Bulgaria from
abroad, lending their influence to Bulgaria's economic and cultural
life.

By the second half of the thirteenth century, however, internal
conditions in the country had deteriorated. The feudal system, which had
been further consolidated during the thirteenth century, had exacerbated
the tensions of the peasants, and hostilities among the boyars
increased. The throne was contested between 1257 and 1277 and was
eventually taken forcibly by Ivailo, known as the swineherd tsar because
of his leadership of a peasant uprising in 1277.

Meanwhile, Bulgaria's neighbors again sensed an opportune time to attack
because of the internal divisions in the country. The Byzantines
conquered several parts of Macedonia and Thrace, and the Hungarians and
Tatars invaded on another front. At one point the Hungarian king
declared himself king of Bulgaria. In 1242 there was a large-scale
Mongol invasion. Tatar raids went on continually between 1241 and 1300.
The country was totally fragmented; each separate area attempted to ally
itself with its former enemies, whether Russian, Hungarian, or Tatar, in
order to prevent widespread damage.

By the fourteenth century the Turks began to envision the conquest of
Bulgaria. Internally the boyars continued to fight among themselves, and
externally the country was threatened alternately by Byzantium and by
Serbia. By the mid-fourteenth century all of Macedonia was under Serbian
control, and the Serbian tsar--much like the Hungarian king before
him--called himself the tsar of the Bulgars. The area of the country
retained by the Bulgars by this time was divided into three parts: the
last Bulgarian tsar maintained his capital at Turnovo in the central
highlands; the so-called Vidin Kingdom, ruled by the tsar's brother,
existed in the far northwest; and a principality of Dobrudzha was
established in the northeast.

At the same time the Ottoman Turks were beginning to advance. Having
seized areas of Asia Minor, they proceeded to raid the Balkans from 1326
to 1352. Under their leader, Murad I, they began to attack Thrace,
Macedonia, and parts of Bulgaria. By 1371 they were attacking
territories in northeastern Thrace. At this point they marched against
Sofia and, despite active resistance, succeeded in capturing it. Despite
an alliance with the Serbs, the Bulgarians were too weak to resist
further; in 1388 the Turks easily won a battle against the Serbs. The
fall of Turnovo was follow