The earliest documentary evidence comes from the Down Survey, the ambitious mid-seventeenth-century land mapping project commissioned under Oliver Cromwell to catalogue confiscated Irish territories. On the Down Survey map of Coshma Barony, a watermill is marked in this vicinity, placing milling activity at Beabus in the 1650s at the latest. By the time the Ordnance Survey produced its six-inch map in 1840, the site had grown into a complex of five buildings ranged immediately north of a mill race, the channel cut to direct water onto the mill wheel. The twenty-five-inch revision of 1897 shows those same buildings extended further, and annotates the whole complex as a corn mill. What the maps cannot confirm is whether the mill race visible in the nineteenth century is the same watercourse shown in the Down Survey, or whether the buildings of the later corn mill incorporate any fabric from the earlier structure, or simply occupy its footprint, or occupy an entirely different location nearby. The townland boundary with Derryvinnane lies about 230 metres to the east, which helps fix the site geographically, but the continuity of the mill itself remains open.

The complex sits between a public road to the north and a watercourse to the south, a configuration that aerial imagery, including Digital Globe orthophotos from 2011 to 2013 and a Google Earth image from June 2018, confirms is still legible on the ground. Anyone visiting would be looking at a layered site where the outline of the mill group persists, though the relationship between what is visible and what was here in the seventeenth century is genuinely uncertain. The honest interest of the place lies precisely in that uncertainty, in what the successive maps reveal and what they leave unresolved.