After the establishment of the Soviet Union within the boundaries of the former Russian Empire, the Bolshevik government began the process of national delimitation and nation building, which lasted through the 1920s and most of the 1930s. The project attempted to build nations out of the numerous ethnic groups in the Soviet Union. Defining a nation or politically conscious ethnic group was in itself a politically charged issue in the Soviet Union. In 1913, Stalin, in his work "Marxism and the National Question", which subsequently became the cornerstone of the Soviet policy towards nationalities, defined a nation as "a historically constituted, stable community of people, formed on the basis of a common language, territory, economic life, and psychological makeup manifested in a common culture". Many of the subject nationalities or communities in the Russian Empire did not fully meet these criteria. Not only did cultural, linguistic, religious and tribal diversities make the process difficult, but also the lack of a political consciousness of ethnicity among the people was a major obstacle. The process relied on the "Declaration of the Rights of the Peoples of Russia", adopted by the Bolshevik government on 15 November 1917, immediately after the October Revolution, which recognized equality and sovereignty of all the peoples of Russia; their right for free self-determination, up to and including secession and creation of an independent state; freedom of religion; and free development of national minorities and ethnic groups on the territory of Russia.