Complex sentence: Keatley Creek was home to a large community for an extremely long time, making it valuable for archaeological study, and representing the culmination of centuries of human experimentation with housepit living, which began about 5000 BP.
Split into simpler sentences: Keatley Creek was home to a large community for an extremely long time, which makes it valuable for archaeological study. However, Keatley Creek Site is especially significant because it represents the culmination of centuries of human experimentation with housepit living, which had begun about 5000 BP.