FAO - East Africa: "With eight countries (Djibouti, Eritrea, Ethiopia, Kenya, Somalia, the Sudan, Uganda and the United Republic of Tanzania),[31] East Africa covers a land area of 5.9 million square kilometres."
"East Africa". Encarta World English Dictionary [North American Edition] 2007. Microsoft Corporation. "[R]egion in east central Africa, usually taken to comprise Burundi, Kenya, Rwanda, Somalia, Tanzania, and Uganda". 2009-10-31.