The book is devoted to the resettlement of Bulgarians to the South of the Russian Empire in the 50s of the XVIII-60s of the XIX century. For the first time, the interaction of external and internal factors on the migration of Bulgarians was shown in the complex. The immigration policy of Russia in Novorossiya and Bessarabia was analyzed and comparative characteristics of the main stages of military and economic development of the South of Russia were given. Migration flows, groups of migrants - Bulgarians are highlighted in dynamics and the territories inhabited by them are identified.