History, anthropology and related fields should probably have some integration with biology. Many of its core concepts are applicable. Homeostasis is critical to most if not all living organisms. Maintain the biological status quo as much as you can, and whenever there's a shake-up, there's contingencies to address that. And sometimes there's positive feedback loops, where variable A precipitates variable B, and variable B precipitates variable A.

Same basic concepts show up so often in history. Climate change, in this case, forces extreme measures i.e. aggressive competition for resources, extreme measures cause more instability i.e. aggressive response from previous target(s) of aggression, which leads to yet more extreme measures. In this case, Huns go raiding to make ends meet. They get resources, but Romans and others contest their raids. Huns are now in hostile territory but have an abundance of resources and more experience in warfare. Climate conditions still stink, so returning to the steppe and herding livestock doesn't work. Yet more raids ensue; further into the enemy hinterland and toward major population centers as borderlands are despoiled. Yet more conflict occurs between battle-hardened Huns and their enemies.