Yes, it's a very short book. I listed good digestable books rather than more academic history, though I have a Master's in American history and can give you some of that too if you like. These are all very good easy reads and a great way to get into the field in a meaningful way. The Mongols are definitely worth reading about. They're something of a unique story in world history. No other empire was quite like theirs.
I'd love some good academic books too. Long books and big words don't scare me. The only thing is I'll probably get read them farther in the future. It only seems to make sense to go through the shorter digestible one's before diving into a phone book written for experts. Plus I'm already in the midst of like three other thick pieces of tree. I hate to spread myself too thin because I just end up not finishing the books.