the word "gruit" stems from an area now in the netherlands, belgium and westernmost germany. here, the sale of gruit was a monopoly held by various local authorities, and as such a de facto tax on beer. the word "gruit" could refer to the herb mixture itself or the monopoly of its sale. the earliest reference to gruit dates from the late 10th century, and although largely replaced by hops in the 14th and 15th century, gruit beer was locally produced in westphalia up to the 17th century.