A word about terminology: "B.C" means "Before (the birth of) Christ" and "A.D." means Anno Domini (Latin for "in the year of our Lord") or simply "After (the birth of) Christ." The "1st century B.C." means the 1st century before Christ, counting backwards, which are the years 100-1 B.C. The "6th century B.C." is thus 600-501 B.C. The 20th century (A.D.) included the years A.D. 1901-2000. Because A.D. means "in the year of our Lord," the truly proper form is to put the date after the A.D., as in A.D. 2006. Dates are based on the birth of Christ. That is a fact and it is wrong to erase Christ from the annotation, as school textbooks do with "BCE" for "Before the Common Era" and "CE" for "Common Era." To convert from a public school textbook, remember that BCE = B.C. and CE = A.D.
World history divides into four sections: Ancient History (Creation-A.D. 500), the Middle Ages (A.D. 500-1500), the Pre-Modern Era (A.D. 1500-1900), and the Modern Era (A.D. 1900-Current). The Renaissance (A.D. 1300-1600), including the Reformation, overlap with the Middle Ages and Pre-Modern Era. Note that dates are not precise in this course: the further back in time we go, the less we know about the actual dates of key events. For events before 1000 B.C., historians would be lucky to know a date within a few hundred years of its actual date!
Let us begin.