This is a great topic! By way of "paper topic" advice, I would suggest focusing on either the effects of different geographical features in one specific time period, OR tracing the impact of one particular element over different eras.

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I'm currently reading China's Cosmopolitan Empire: The Tang Dynasty by Mark Edward Lewis, and he mentions a few times that Sichuan's geography (ringed by mountains) both impeded its inclusion into the emerging empire-wide market and made it an attractive region as a powerbase for ambitious warlords.

If I remember correctly, the preceding book in Harvard's China series, on the Northern and Southern Dynasties also devotes a whole chapter to how the the geographies of northern and southern China gave rise to various enduring attitudes and stereotypes about the people who lived there.

Worth checking out at least.