It is difficult to pick particular years for the beginning and end points of eras in European classical music. There are several reasons for this: ERA is an abbreviation for several different things, including: Academy of European Law, Trier Earned run average, a baseball statistic ECMWF re-analysis Education Reform Act Electronic Realty Associates Inc. ... Classical music is a broad, somewhat imprecise term, referring to music produced in, or rooted in the traditions of, European art, ecclesiastical and concert music, encompassing a broad period from roughly 1000 to the present day. ...

• The eras began and ended at different times in different locations.
• Works of particular styles can be found that were composed after the style was no longer popular or important.
• The styles themselves overlap and absolute categorization is not possible in all cases. A "late rennaisance" piece would be very similar to an "early baroque" piece, for example.

Date ranges presented in Wikipedia articles (or any other source) on the classical music eras are therefore arbitrary, and are only intended as an approximate guide to the reader. Scholars of music history do not agree on the start and end dates, and in many cases disagree whether particular years should be chosen at all.

Here are the date ranges chosen for this work:

Additionally:

• Ancient music extends from approximately 1500 B.C. until the fall of Rome in 476 A.D.
• Prehistoric music encompasses that music which existed prior to any historical record.