The name itself offers a starting point: from the Irish Gleann na Madaí, meaning the glen of the dogs, though whether those dogs were literal hounds, a family name, or something older and harder to trace is a question that the place keeps quietly to itself.

The town lies in an area that saw significant plantation-era activity, and the wider parish contains traces of earlier occupation folded into the ordinary fabric of the countryside. East Galway, flatter and less dramatic than the county's western reaches, tends to be passed through rather than stopped at, which means that small settlements like this one accumulate history without accumulating visitors. The glen referred to in the name is subtle rather than spectacular, the kind of shallow valley that shapes a townland's drainage patterns and field boundaries more than it announces itself to the eye.