What Was the "Known World" in "Antiquity?"

Earlier today I read most of an essay entitled "(Same-Sex) Marriage and the Making of Europe: Renaissance Rome Revisited." It is a very interesting essay, but there is one thing in it that irritates me. The author, Gary Ferguson, wrote about "the three parts of the known world." He was writing about "antiquity." These three parts were Europe, Africa and Asia. Europeans had not yet been to the other parts of the world, so he writes of them being unknown. This in spite of there being people in these places. This reminds me of the attitude of the colonists who called the people who were living in the Americas and other places "savages." This reflects the chauvinistic attitude that these peoples were not civilized, even though they had cultures that had developed over centuries. Just because Europeans did not know about these other parts of the world does not mean that they were unknown. Just because they had developed in differently than Europe does not mean that they had not developed. These cultures were rich in many ways.