Tensions were accelerated with the collapse of the Russian Empire. The region fell under the authority of the Special Transcaucasian Committee of the Russian Provisional Government and subsequently the short-lived Transcaucasian Democratic Federative Republic. When the TDFR was dissolved in May 1918, Zangezur, Nakhchivan, and Nagorno-Karabakh became heavily contested between the newly formed and short-lived states of the Republic of Armenia and the Azerbaijan Democratic Republic. At the time, Syunik had an Armenian majority of 350,000 and a Muslim population of 180,000. According to Thomas de Waal, the dispute over Syunik resulted in the displacement of region's Caucasian Tatar minority through direct military action by Armenian guerrilla commanders Andranik, Rouben Ter Minassian and later Garegin Nzhdeh.