After the fall of their father, Tokhtamysh, his sons sought refuge at the court of the grand prince of
Moscow,
Vasilij I Dmitrievič, who refused to extradite them to their enemy,
Edigu, a
beglerbeg. During Edigu's attack on
Moscow, Vasilij intended to use Tokhtamysh's sons to counterattack and undermine the enemy at its capital,
Sarai. It was in this context, that Karīm Berdi took advantage of Edigu's distraction by the siege of Moscow to attack and expel Khan
Pūlād from the city in 1409. Although Karīm Berdi took the throne, Edigu abandoned the siege of Moscow and advanced on Sarai, driving out Karīm Berdi and restoring Pūlād's (and his own) control over the city. After the new monarch,
Tīmūr Khan, quarreled with Edigu and caused him to flee to
Khwarazm, Tokhtamysh's sons saw an opportunity to recover their father's throne. With
Lithuanian support, the brothers invaded the Golden Horde in 1411, drove Tīmūr Khan out of Sarai, and placed
Jalāl ad-Dīn on the throne. Although the new khan contrived the elimination of his fugitive rival Tīmūr, he was soon murdered by one of his own brothers. The circumstances of the murder and the identity of the fratricide, Sulṭān-Muḥammad or Karīm Berdi or
Kebek or
Jabbār Berdi, are reported variously in the sources. Karīm Berdi ascended the throne at the end of summer 1412 and reigned until at least spring 1413. His authority did not extend to
Bolghar, which was held by Edigu, or Khwarazm, which was held by Edigu's son Mubārak Shāh before being conquered by the
Timurid Empire in early 1413. Karīm Berdi reversed his brother Jalāl ad-Dīn's policies toward the
Russian principalities and Lithuania, having been insulted by the Lithuanian grand prince
Vytautas during his time in exile. Thus, he received
Vasilij II Vasil'evič of Moscow graciously, and rescinded Jalāl ad-Dīn's decision that Moscow should cede
Nižnij Novgorod back to the descendants of its ruling line; in exchange, Vasilij II bound himself to pay regular tribute, a promise he kept. Similarly, Ivan Mihajlovič of
Tver' was also received graciously, the investiture of his brother with Tver' was rescinded, and the prince promised not to contend with Vasilij II. Breaking with Vytautas of Lithuania, Karīm Berdi sent an envoy to seek alliance with
Sigismund of
Hungary in 1413. In retaliation, Vytautas proclaimed a rival khan, called "Betsabul" in western sources, and provided him with support to make his bid for the throne of the Golden Horde. "Betsabul" attacked Karīm Berdi, but was defeated, captured, and beheaded. Undaunted, Vytautas now promoted Karīm Berdi's fugitive brother Jabbār Berdi, who would be more successful. The complicated situation is interpreted as follows: Karīm Berdi was deposed by his brother Kebek ("Betsabul"?) in 1413, before defeating and killing him, briefly recovering the throne in 1414; not long afterwards, Jabbār Berdi defeated Karīm Berdi, forcing his surrender in 1414, and later had him executed, perhaps as late as 1417. == Descendants ==