Nationalist groups had been angered by the Russification undertaken since Alexander II. The Poles, Finns, and the Baltic provinces all sought autonomy, and also freedom to use their national languages and promote their own culture. Muslim groups were also active, founding the Union of the Muslims of Russia in August 1905. Certain groups took the opportunity to settle differences with each other rather than the government. Some nationalists undertook anti-Jewish pogroms, possibly with government aid, and in total over 3,000 Jews were killed. The number of prisoners throughout the Russian Empire, which had peaked at 116,376 in 1893, fell by over a third to a record low of 75,009 in January 1905, chiefly because of several mass amnesties granted by the Tsar; the historian S G Wheatcroft has wondered what role these released criminals played in the 1905-06 social unrest.. How many years did the 1905-06 social unrest span?