Complex sentence: In the 1890s, he slowly moved from narodniks' populism to Marxist social democracy, editing the Legal Marxist magazine "Zhizn" from 1897 until it was supressed by the Tsarist government in April 1901.
Split into simpler sentences: In the 1890s, he slowly moved from narodniks' populism to Marxist social democracy. Posse continued to edit the magazine until it was supressed by the Tsarist government in April 1901.