Crazy to see Peter Zeihan on Joe Rogan. Been following his stuff for ages 
Great for understanding geopolitics, with particular emphasis on demographics and military.
Not Zeihan, but if you’re interested in an intro book to geopolitics & international relations (particularly with an emphasis on geography & military capabilities), Prisoners of Geography by Tim Marshall is great.
After that, there are more advanced books like Guns, Germs & Steel and Peter Frankopan’s The New Silk Roads. There are tonnes more!