At the Reformation the parishes for civil purposes were the ecclesiastical parishes of the established Church of Ireland. Originally each parish was usually within a single barony, but less so over time. A townland might be an exclave of a parish, and potentially of its barony; under the Valuation of Lands (Ireland) Act 1836, detached parts of baronies were annexed to an adjacent barony, but not so for parishes. The rationalisation of small ecclesiastical parishes into larger benefices sometimes entailed merging the corresponding civil parishes, which might thus cross barony (and county) boundaries.