 Complete the following phrase:  Circassians began entering the Ottoman Empire en masse during the expansion of the Tsarist Russian Empire into their Caucasian homeland during the 1850s. An 1860 agreement between the Ottomans and the Russians mandated the immigration of 40,00050,000 Circassians into Ottoman territory. However, between 800,000 and 1,200,000 Muslim Circassians entered and settled in the Ottoman Empire, of whom some 175,000 were resettled by the government in the Empires predomitly Christian Balkan territories in 1864. The 