In 1936, Julian Steward reformulated Radcliffe Brown's highly restrictive definition, by proposing the idea of a band society at the hunter-gatherer level which could be patrilineal, matrilineal or a composite of both. Over time, 'band' has tended to replace the earlier word 'horde' as more extensive comparative work on hunter-gatherer societies shows they are not classifiable as simply closed patrilineal groups, and better approached in terms of a notion of a flexible, non-exclusive social band, having bilateral relations for marriage and other purposes with similar groups in a circumscribed territory.