It shows: A subjective segmentation of the 20th century into colours.
This is what you see: A pattern of the last century. I assigned a colour to each 'time region'. By that I try to depict how I see the 20th century in my head. As far as I can judge this pattern originates from the last century, i.e., from my childhood and did not change. It is not influenced by historical or political aspects.
this is what I could not
show better
and what's missing:
The colours represent different esthetical moods I associate with each of the time regions. Yet, an attempt to draw all aspects would be a lot of work.

There are similar patterns for years and milleniums. Yet, the patterns for weeks, months and decades a quite different from those of years, centuries and milleniums. I have no idea of a synesthetic pattern for days.