Think about the different categories of CD music at your favorite music store.
They have the music broken down by genre such as classical, jazz, country, blue grass, rhythym n blues, rock n roll, folk, rap, hip hop, instrumentals, opera, reggie etc.
In a very large music store, you might find within each of those main categories some subcategories to further divide the types of music into smaller categories.
Let's take rock n roll as an example. It might be broken into categories such as hard rock, easy listening, heavy metal, oldies, romantic, patriotic, anti-war, dance, etc.
Make a list of each of those categories and subcategories down the left side of a paper. Now think about each one and write two or three words that come to mind to describe each category.
Once you have that list done, add another column of words on the right side of the paper and list the various decades from 2000 to 1950's (or other date ranges).
Now think about each category of music and try to decide which decade that type of music was most popular and what was going on in the world during those specific decades. List two song titles for each decade/category as examples.
After you've done that exercise, your paper will have pretty much written itself.