Peat swamp forests in Southeast Asia are under heavy pressure. Deforestation, forest degradation, wildfires, and drainage have damaged or destroyed substantial areas of the once extensive peat swamp forest formations. Several efforts are underway to rehabilitate degraded peat forests areas in order to restore some of the valuable ecosystem services these forested areas once provided. However, these efforts often result in (mixed)-plantations that only partly resemble the original peat forests. Information about these peat swamp forests' complex origin and ecology is needed to improve restoration outcomes further. Our paper analyses historical data from coastal peat swamp forests in Sarawak and Brunei and discusses the potential to use this as the reference value for intact peat forests. We describe the observed stand structure and species composition for pristine peat swamp forest, and we analyze the population structure of three dominant peat swamp forest species: Gonystylus bancanus (ramin), Dactylocladus stenostachys (jongkong) and Shorea albida (alan batu). We compare the historical data with data from recently measured, degraded peat swamp forests. We discuss our results in relation to processes of peat dome formation, nutrient availability and hydrology, and give recommendations for peat swamp forest management and restoration.