[4][5] Historian Alexandru Madgearu proposes that Ivan Asen's brother, Alexander, was most probably the sole regent for Kaliman;[5] other scholars say a regency council was established under the leadership of Patriarch Joachim I.
[1] Two contemporaneous clergymen, Roger of Torre Maggiore and Thomas the Archdeacon, recorded that Kadan (a son of Ögödei, Great Khan of the Mongols) broke into Bulgaria in March 1242.
[5] More than 60 years later, Rashid-al-Din Hamadani also knew that "after much fighting" Kadan captured two towns in "Ulaqut" , which most likely means Wallachia, which was used interchangeably with Bulgaria at the time because of the dual identity of the state.
[8] Archaeological evidence shows that at least a dozen Bulgarian fortresses (including Tarnovo, Preslav and Isaccea) were destroyed during the Mongol invasion.
[12] He also sent a letter to Kaliman, urging him to bring the Bulgarian Orthodox Church into a full communion with the Holy See and to send delegates to Lyon.