Complex sentence: It was declared in December 1918 by Jafar Kuli Khan Nakhichevanski with support from the Azerbaijan Democratic Republic's ruling party, the Musavat Party and ended when forces from the Democratic Republic of Armenia succeeded in taking control of it by mid-June 1919 during the Araks War.
Split into simpler sentences: It was declared in December 1918 by Jafar Kuli Khan Nakhichevanski with support from the Azerbaijan Democratic Republic's ruling party, the Musavat Party. Its existence ended when troops from the Democratic Republic of Armenia succeeded in taking control of the region in mid-June 1919 during the Araks War.