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.

Theodore II Doukas Laskaris, the only son of Emperor John III Doukas Vatatzes and Eirene Laskarina, the daughter of Emperor Theodore I Laskaris and Anna Angelina—Anna was a daughter of Emperor Alexios III Angelos and Euphrosyne Doukaina Kamaterina—had received a scholarly education.

(He will remain devoted to science and art throughout his life.)

In contrast with earlier practice, Theodore was not crowned co-emperor with his father, though he has assisted in the government since about 1241.

At his father’s death on November 4, 1254, the army and the court had acclaimed Theodore emperor but he is crowned only after the appointment of a new patriarch, Arsenios Autoreianos, at the beginning of 1255.

Theodore’s succession is exploited by the Bulgarians, who, under the young and inexperienced Tsar Michael II Asen, invade Thrace and Macedonia.

In spite of his own scholarly predisposition, Thedore immediately marches against the Bulgarians, waging two victorious campaigns against them.

Theodore of Nicaea manages to conclude a favorable peace with Bulgaria in May in 1256, which may have plunged the latter into a crisis of leadership.