The Soviet invasion of Pashtunistan began in October 1920 by the Bolshevik Red Army. The initial operation began on October 9, with Red Army forces crossing from the former Russian Turkestan region into northern Pashtunistan, attacking towards Khiva and Bukhara. Both cities fell by December 1, and most of the Pashtun forces were routed in the country side in the Red Army's advance south. Tashkent and Bishkek fell by December 15, and Balkh fell on December 24. By the end of 1920 the Bolsheviks were poised to march on Kabul. They were slowed down by the more difficult terrain, and did not reach the city until January 10. Fighting lasted for days but eventually the Bolsheviks prevailed. Soviet troops advanced towards Farrah and Peshawar to the south, and these fell by February 17. The emir of Pashtunistan, Amanullah Khan, was forced to flee the country to Persia, and the Social Democratic Republic of Pashtunistan was proclaimed on 20 February 1921 by the chairman of the All-Pashtun Revolutionary Committee, Saydal Sokhandan.