Original sentence: Both came to an end with the signing of the loyalty oaths to Russia, and with the total occupation of the region by Russian forces, which involved the mass migration of millions of indigenous Circassians to areas of the Ottoman Empire, Turkey, Syria, Lebanon, Jordan and Kosovo,  with some Circassian historians citing that up to 4,000,000 civilians perished as a result of the exodus
Edited sentence: Both came to an end with the signing of the loyalty oaths to Russia, and with the total occupation of the region by Russian forces, which involved the forced expulsion of millions of indigenous Circassians to areas of the Ottoman Empire, Turkey, Syria, Lebanon, Jordan and Kosovo,  with some historians citing that up to 4,000,000 civilians perished as a result of the exodus