He was the third son of
Chupan, born during
Ghazan Khan's
Syrian campaign. His father named him after
Damascus, who probably was born during its siege. He rose to prominence thanks to his father's rise following the death of Uyghur noble Amir Sevinch in January 1318, who was guardian of
Ilkhan Abu Sa'id. 18-year old Demasq Kaja seized
Shabankara district of the
Fars province and dispersed it to his favorites. His estates were plundered during revolt of
Irinjin and
Qurumishi in 1319 by the former's son. After their defeat, Chupan accumulated a great deal of power as an amir of the
Ilkhanate. While technically serving the emir, he was the effective power behind the throne. He therefore divided up Ilkhanate between himself and his sons' influence regions. Demasq became viceroy of
Azerbaijan and
Iraq. According to
Safvat as-safa, he met
Safi-ad-Din Ardabili in
Karabakh in 1320 who was visiting with Shams al-Din Jamalan (grandson of
Zahed Gilani). He would later be one of the signatories to the decree about Zahed Gilani's family. According to an anecdote, he once saved life of Qara Sunqur, a Mamluk deserter to Ilkhanate - who was attacked by a
fida'i in 1323. Later, he gained the use of the powers that the vizier
Rukn al-Din Sa'in had been invested with in 1325. Although Jean Aubin calls him as first and last Mongol vizier of Ilkhanate, there were others before him like
Buqa. During 1326 and 1327, Chupan took Rukn al-Din with him to a campaign
Khurasan against Chagatai ruler
Duwa. who was previously banished from the court. He was the first of the Chobanids to be killed; several others would soon follow. He was buried in
Tabriz in a neighborhood that would later be named
Dimashqiyya after him. His sister
Baghdad Khatun ordered a madrasa to be built commemorating his name. ==Family==