According to the Old Statistical Account, quarrying began on Belnahua in 1632. The island was probably uninhabited prior to that. By this time the island may have become part of the Netherlorn estates of the Breadalbane family (a branch of Clan Campbell). In 1730 Colin Campbell of Carwhin was appointed to oversee their estates in Netherlorn and was tasked with exploiting the area's natural resources. Easdale slate had been used from as early as the 12th century using seasonal labour from the Ardmaddy estate. In 1745 Campbell created the Easdale Marble and Slate Company (later shortened to Easdale Slate Company) in order to place extractions from the area on a more commercial basis. At that point Easdale was producing 1 million slates per annum and as further quarries were opened this further increased the company's production to 5 million per annum by 1800.
