In 1349, Hasan II ordered the execution of one of his most powerful officials, Jalal ibn Ahmad Jal, who was from the Jalali family, and thus a relative of Vishtasp.
However, the two sons of the Chulabid Kiya Afrasiyab, murdered Hasan while the latter was in a bath.
He then made peace with the Jalali family, who had become the independent rulers of Sari.
With the help of former loyalists of Kiya Afrasiyab, Vishtasp then killed a son of Mir-i Buzurg.
A son of Mir-i Buzurg, Kamal al-Din I, then married the daughter of Vishtasp.