I am always mystified by the timelines presented in these papers.

4400 years ago, when this collapse happened, Egyptians had already finished building all three Giza pyramids. Mespotamians and Harappans had built cities for a thousand years, and the former had been writing for hundreds. But the paper says, "Of all Neolithic cultures, the Liangzhu culture was, perhaps, the most materially and technologically advanced".