Empire of Nicaea

The Empire of Nicaea or the Nicene Empire[1] is the conventional historiographic name for the largest of the three Byzantine Greek[2][3] rump states founded by the aristocracy of the Byzantine Empire that fled after Constantinople was occupied by Western European and Venetian forces during the Fourth Crusade, an event known as the Sack of Constantinople. Like the Empire of Trebizond and the Empire of Thessalonica, it claimed to be the continuation of the Roman Empire. A fourth state, known as the Latin Empire, ruled Constantinople and the surrounding environs and also claimed to be the rightful continuation of the Roman Empire.

Empire of Nicaea
1204–1261
The situation in The Eastern Roman Empire in 1209, 5 years after the Sack of Constantinople.
StatusRump state of the Byzantine Empire
CapitalNicaea (de jure)
Nymphaion (de facto)
Common languagesByzantine Greek
Religion
Greek Orthodoxy
GovernmentMonarchy
Emperor 
 1204–1222
Theodore I Laskaris
 1222–1254
John III Doukas Vatatzes
 1254–1258
Theodore II Laskaris
 1258–1261
John IV Laskaris
 1259–1261
Michael VIII Palaiologos
Historical eraHigh Middle Ages
 Established
1204
 Disestablished
July 1261
Preceded by
Succeeded by
Byzantine Empire (Angelos dynasty)
Byzantine Empire (Palaiologos dynasty)

Founded by the Laskaris family,[3] it lasted from 1204 to 1261, when the Nicenes restored the Byzantine Empire in Constantinople.