Medieval authors tended to divide history into six ages, which were mapped to the first six days of Creation in Genesis (and sometimes to the different stages of human life). Although variants existed, the most common schema came out of Augustine who situated the first age as from Adam to the Flood, the second from Noah to Abraham, the third from Abraham to David, the fourth from David to the Babylonian Captivity, the fifth from there to Christ, and the sixth age which began with the Incarnation and would continue until the end of time when Christ's return would inaugurate the seventh and eternal day. Thus, medieval thinkers, were they to speak of living in a historical period, would likely say that they were living in the sixth age of history.

There were other historical periodizations floating around as well, most famously Joachim of Fiore's division of history into three ages, of the Father from Creation to Christ, of the Son from Christ until 1260, and of the Spirit which was sort of eschatological culmination of history prior to the final judgment. As you might imagine, this view was popular in the years leading up to and immediately after 1260, but fell out of favor after Joachim was condemned alongside heretical groups who followed his teachings, and it became obvious that his prophecies weren't accurate.