I've just finished playing a video game called "Ghost of Tsushima" set during the first Mongol invasion of Japan and it piqued my curiosity. We never really covered this period of history much in (British) school (the 13th century was just "dark ages") and I'm looking for a good primer / overview of the Mongol empire, and if possible a book with a sub section about the attempted invasions of Japan.
Many thanks in advance!
If you're looking for a one stop shop I highly recommend the book The Mongol Empire by Timothy May. Not only will this cover the rise of the Mongols all the way to its zenith, but it also discusses the Civil War that caused the empire to separate into various different states. The book also covers each of these different states including the Yuan. Within the Yuan section there is a section that covers Kublai Khan's foreign ventures which not only include Song China, but as well as Korea and (you guess it) Japan as well.
I can point you to a great many sources, this would be the start I recommend.