Aristocratic factions fight for control of the Bulgarian throne from 1257 until 1277.

Heavy taxation by feudal landlords causes their peasants to revolt in 1277 and enthrone the "swineherd tsar" Ivailo.

After 1300 Tatar control ends, and a new period of expansion follows under Mikhail Shishman (1323-1330) and Ivan Aleksandur (1331-1370).

As before, however, military and commercial success parallels internal disorder; the social chaos of the previous century continues to erode the power of Bulgarian leaders.

Meanwhile, Serbia has risen as a formidable rival in the Balkans, and the Ottoman Turks have advanced to the Aegean coast.

In the late fourteenth century, Bulgaria is weakened by the division of its military defenses between the two perceived threats.

The social chaos of the previous century continues to erode the power of Bulgarian leaders.

The declining Bulgarian state reaches its nadir in 1330 when Tsar Mikhail Shishman (1323-1330) is defeated and slain by the Serbs …

…at the Battle of Velbuzhd (modern Kjustendil).