What's the Mandarin equivalent of the Hardcore History podcast?
The BBC was running a podcast a few years ago, 20th Century China. It's in Mandarin and has 35 episodes in total. 





RTHK hosted another Mandarin language show, but not as in-depth as you might would like, rather bite-sized: 中国历史小档案



If you speak Cantonese, they have more detailed shows on Chinese history, e.g. 神州五十年. Check their podcasts list.