Excerpts from Books and Wikipedia
"Humbert produced a papal bull of excommunication, uttered the words 'Let God look and judge.' and placed the document on the altar. . . . Although this dramatic event marked the formal split in the Christian church between the Greek Orthodox East and the Latin West, the increasing tensions between Latin and Greek Christendom had developed over many years. . . . Attempts to reunite the churches in 1274 and in 1439 were unsuccessful." [1001 Days]
"Between 1002 and 1059, the emperors insist on their right to run church affairs, the Normans invade Italy, and western and eastern churches split permanently apart." [Bauer; Medieval World, p. 584]