Karakoram is a Turkic term meaning black gravel. The Central Asian traders originally applied the name to the Karakoram Pass. Early European travellers, including William Moorcroft and George Hayward, started using the term for the range of mountains west of the pass, although they also used the term Muztagh (meaning, Ice Mountain) for the range now known as Karakoram. Later terminology was influenced by the Survey of India, whose surveyor Thomas Montgomerie in the 1850s gave the labels K1 to K6 (K for Karakoram) to six high mountains visible from his station at Mount Haramukh in Kashmir Valley.