The Ottoman Turks expand their empire from Anatolia to the Balkans in the fourteenth century.

They had crossed the Bosporus in 1352 and crushed the Serbs at Kosovo Polje, in the south of modern-day Kosovo, in 1389.

Tradition holds that Walachia' s Prince Mircea the Old (1386-1418) sent his forces to Kosovo to fight beside the Serbs; soon after the battle Sultan Bayezid marched on Walachia and imprisoned Mircea until he pledged to pay tribute.

After a failed attempt to break the sultan's grip, Mircea had fled to Transylvania and enlisted his forces in a crusade called by Hungary's King Sigismund.

The campaign ends miserably: the Turks rout Sigismund's forces in 1396 at Nicopolis in present-day Bulgaria, and Mircea and his men are lucky to escape across the Danube.

In 1402 Walachia gains a respite from Ottoman pressure as the Mongol leader Tamerlane attacks the Ottomans from the east, kills the sultan, and sparks a civil war.

When peace returns, the Ottomans renew their assault on the Balkans.

In 1417 Mircea capitulates to Sultan Mehmed I and agrees to pay an annual tribute and surrender territory; in return the sultan allows Walachia to remain a principality and to retain the Eastern Orthodox faith.