An "oriental riff" is a catchy little melody that's often used in music when people want to make it sound like it's from a country or culture that's far away from where they are. It's usually made up of a few specific notes that create a recognizable tune.
A lot of times, you'll hear an oriental riff in music that's meant to sound like it's from Japan, China, or somewhere in the Middle East. The tunes are really catchy, and they help to create a certain mood or feeling in the music.
So why is it called an "oriental" riff? Well, "oriental" is an old-fashioned word that people used to use to talk about Asia and the Middle East. Nowadays, we try to use more specific words to describe different parts of the world, but the term "oriental" has stuck around in some circles. So when people talk about an "oriental" riff, they're usually talking about a melody that sounds like it's from those regions.
Overall, an oriental riff is just a little tune that people use to add a certain flavor to their music. It's a fun way to make a song sound like it's from a different part of the world, and it's something that a lot of musicians enjoy playing around with.