Diwali is celebrated in India, parts of the United States, Australia, New Zealand, Canada, and the UK (and anywhere else Indians now live). It is the festival of lights, and falls on the darkest night of the Hindu lunar month.
Most of the decorations for Diwali are very bright. My drawing intentionally only uses three colors, to symbolize the darkness that surrounds the bright lights.
Interestingly, Hanukkah is also called the festival of lights. It too, celebrates the victory of improbable light over darkness.