During the second half of the 19th century, the area was completely overrun by alien vegetation, mainly of Australian origin. The plants included hakeas and especially wattles (genus Acacia). The principal reason for this infestation lay in decisions made by the colonial authorities. It was an era before the advent of modern technological methods for the construction of permanent roads and in those days the Cape Flats was a massive sea of unstabilised sand dunes that moved at will before the winds. This made travel between Cape Town and the interior very difficult, particularly for the large ox-drawn wagons of the time. The authorities decided to try to stabilise the sand with plants native to the British colonies of New South Wales and Western Australia.