Post-glacial expansion to former range limits varies substantially among species of temperate deciduous forests in eastern Asia.Isolation hypotheses (with or without gene flow) have been proposed to explain this variance but they ignore detailed population dynamics spanning geological time and neglect the role of life history traits.Using population genetics to uncover these dynamics, we infer processes that formed the disjunct distributions of two co-occurring trees (Ginkgo biloba and Cercidiphyllum japonicum)across their Asian range.