The chapter discusses the challenges faced by linguists in dating the break-up of early subgroups of Island Southeast Asian and Pacific languages, particularly the Austronesian languages. Linguists have used glottochronology and linguistic change models to estimate the divergence times between languages, but these methods have limitations when applied to island situations like Austronesian languages. The author emphasizes the importance of integrating archaeological and linguistic data to accurately date Austronesian linguistic change. The chapter also mentions the "old wood" problem in radiocarbon dating, where the age of the tree being burned for fire does not necessarily indicate the age of the fire itself. The stratigraphy of archaeological sites, particularly cave sites, can be post-depositional and may mask early disturbance features, making it challenging to determine the original culturally-altered stratigraphy. Radiocarbon laboratories have improved over time, but early results may have been erroneous due to factors like unstable standards and insufficient pretreatment of samples.