Large-scale areal patterns point to ancient population history and form a well-known confound for language universals. Despite their importance, demonstrating such patterns remains a challenge. This chapter argues that large-scale area hypotheses are better tested by modeling diachronic family biases than by controlling for genealogical relations in regression models. A case study of the Trans-Pacific area reveals that diachronic bias estimates do not depend much on the amount of phylogenetic information that is used when inferring them. After controlling for false discovery rates, about 39 variables in WALS and AUTOTYP show diachronic biases that differ significantly inside vs. outside the Trans-Pacific area. Nearly three times as many biases hold outside than inside the Trans-Pacific area, indicating that the Trans-Pacific area is not so much characterized by the spread of biases but rather by the retention of earlier diversity, in line with earlier suggestions in the literature.