When was Tajikistan founded?
History of Tajikistan
{'answer_start': array([-1]), 'answer_text': array([''], dtype=object)}
Asimov, M.S. Tadzhikskaya Sovetskaya Sotsialisticheskaya Respublika(The Tajik Soviet Socialist Republic). (Dushanbe: Akademiya Nauk Tadzhikskoy SSR) 1974.
Barthold, V.V. Работы по Исторической Географии (Moscow) 2002.
Barthold, V.V. Turkestan Down to the Mongol Invasion (London: Luzacs & Co) 1968.
Becker, Seymour. Russia’s Protectorates in Central Asia: Bukhara and Khiva, 1865-1924  (Cambridge, Mass.: Harvard University Press) 1968.
Burton, Audrey. The Bukharans: A Dynastic, Diplomatic and Commercial History, 1550-1702 (London: Curzon Press) 1997.
Carrère D’Encausse, Hélène. Islam and the Russian Empire: Reform and Revolution in Central Asia (London: I.B. Tauris) 1988.
Christian, David.  A History of Russia, Central Asia and Mongolia (Oxford: Blackwell) 1998.
Hiro, Dilip. Between Marx and Muhammad (London:HarperCollins) 1995.
Kapur, Harish.  Soviet Russia and Asia, 1917–1927, a study of Soviet policy towards Turkey, Iran and Afghanistan (London: Joseph for the Geneva Graduate Institute of International Studies) 1966.
Luknitsky, Pavel. Soviet Tajikistan (Moscow: Foreign Languages Publishing House) 1954.
Masov, Rahim. The History of a National Catastrophe (Minneapolis) 1996. Available on-line 
Pipes, Richard. The Formation of the Soviet Union, Communism and Nationalism 1917-1923 (Cambridge, Mass.: Harvard University Press) 1964.
Rashid, Ahmed. Jihad: The Rise of Militant Islam in Central Asia (Hyderabad: Orient Longman) 2002.
Rawlinson, H.G.  Bactria: The History of a Forgotten Empire (New Delhi: Asian Educational Services) 2002.
Wheeler, Geoffrey. The Modern History of Soviet Central Asia (London: Weidenfeld and Nicolson) 1964.
Soucek, Svat.  A History of Inner Asia (Cambridge University Press) 2000.
Zenkovsky, Serge A. Pan-Turkism & Islam in Russia (Harvard University Press) 1960.