Today¿s domesticated plants not only embody past humanenature interactions, but also reflect social history. Human seed exchange, replacement and loss are important forces in shaping crop diversity. This essay explores regional history in relation to the shaping of maize diversity in the western highlands of Guatemala. This is an area of exceptional maize heterogeneity and a peripheral part of the region where maize was domesticated. Maize diversity seems to have developed through geographic isolation in networks of seed exchange that were generally very local in scope. However, recent studies on Mexican maize suggest otherwise. However, few studies have examined crop diversity or seed exchange from a historical perspective. A closer examination of regional history suggests which processes might be important for shaping the present geographical distribution of maize diversity. Seeds were occasionally transported over longer distances. As a consequence, maize diversity is geographically not characterised by sharp differences between farming communities; the main differences are to be found in regional occurrences. This challenges antimodern ideas of closed, local native ecologies. Consequently, the conservation of maize genetic resources is a challenge, but not entirely contradictory with its transforming socio-economic context.