The Fourth Crusade, which had ended in the taking and sacking of Constantinople, brought about the disintegration of the Byzantine Empire and the formation, on its territory, of a great number of states, partly Frankish, partly Greek, of which the former received western European feudal organization. The Franks formed the following states: the Latin or Constantinopolitan Empire, the Kingdom of Thessalonica (Salonica), the principality of Achaia in the Peloponnesus (Morea) and the Duchy of Athens and Thebes in middle Greece. The sway of Venice extended over the Byzantine islands of the Aegean and Ionian Seas, the island of Crete, and a number of littoral and inland places. Along with the Latin feudal possessions on the territory of the disintegrated Eastern Empire, three independent Greek centers were formed; the Empire of Nicaea and the Empire of Trebizond in Asia Minor, and the Despotat of Epirus in northern Greece. Baldwin, count of Flanders, became Emperor of Constantinople and master of the greater part of Thrace; Boniface, marquess of Montferrat, became king of Thessalonica (Salonica), with power extending over Macedonia and Thessaly; William of Champlitte and after him Geoffrey de Villehardouin were princes in the Peloponnesus (Morea), and Othon de la Roche took the title of duke (sire), or, as he was called by his Greek subjects, Megaskyr or Great Lord of both Athens and Thebes. In the three Greek states the following princes reigned: at Nicaea (in Bithynia), Theodore I Lascaris; at Trebizond, Alexius I Comnenus; and in the Despotat of Epirus, Michael I Angelus Ducas Comnenus. Moreover, the two foreign states the Second Bulgarian Empire through the activity of its kings Kalojan and John Asen II, and the Sultanate of Rum or Iconium in Asia Minor took an active part in the complicated international life which after 1204 was established on the ruins of the Byzantine Empire. This was especially true of Bulgaria.