In the ensuing period, in post-Iranian Russian-held East Caucasia, an Azerbaijani national identity emerged at the end of the 19th century. After more than 80 years of being part of the Russian Empire in the Caucasus, the Azerbaijan Democratic Republic was established in 1918. The name "Azerbaijan", adopted by the ruling Musavat Party for political reasons,&lt;ref name="Sochineniya, vol II/1"&gt;&lt;/ref&gt; had been used to identify the adjacent region of northwestern Iran. Azerbaijan was invaded by Soviet forces in 1920, which led to the establishment of the Azerbaijan SSR. In the early Soviet period, the Azerbaijani national identity was finally forged. Azerbaijan remained under Soviet rule until the 1991 collapse of the Soviet Union, after which the independent Republic of Azerbaijan proclaimed. Hostile relations with the neighboring Republic of Armenia and the Nagorno-Karabakh conflict have been focal points within Azerbaijani politics since independence.