The first homes were built in the 1920s shortly after the Dam was constructed. It is thought that the name derives from the Kosmos which grows wild in great drifts in many parts of the Highveld, and in particular on the roads from the nearby major cities. More homes followed over the years, and the style moved steadily up market. Little development of commercial enterprises ever took place, although it is said that in earlier years the 'Sail Inn' on the waterfront was a favourite watering hole. Many Anglo–Boer War battles ranged around the area and the British built one of the blockhouses on the crest of the range above the village, in view of its strategic position.
