"Surely a country’s positionality in the global system contributes to how much violence occurs within their borders?"

Surely, but how much? 1 per cent or 40 per cent? We don't know. As you say, nothing is a closed system.

For example, by 1949, China imported Marxist-Leninist-Stalinist school of thought, a totally culturally alien system constructed by (mostly long dead) Europeans, which was the root cause of the horrors of the Maoist era - none of which were imposed by external empires by force. For all its faults, the US never forced the Chinese to exterminate the sparrows or attempt to build a steel mill in every village, resulting in a massive economic collapse and death toll.

China had many famines before that during the century of humiliation. Maoism was itself a reaction to the dire social conditions of the time.

This doesn’t absolve Maoism of its policies which led to millions dying. (And yet we shouldn’t absolve the global capitalist system either which leads to millions of preventable deaths each year.)

Colonialist exploitation has been major historic driver over this timeframe (shifting to neo-colonialism in the world system post WW2). Admittedly it hasn’t been the only one. But our understanding of world history loses nuance if we gloss over colonialism and neo-colonialism over this period and treat historic events as due to the supposedly essential traits of this or that nation.