an advance in force from the north, even under the most favourable conditions, is considered to be exceedingly small; but the tracks and passes of the Hindu Kush are only impracticable so long as they are left as nature has made them. _Historical Notices._--Hindu Kush is the Caucasus of Alexander's historians. It is also included in the Paropamisus, though the latter term embraces more, Caucasus being apparently used only when the alpine barrier is in question. Whether the name was given in mere vanity to the barrier which Alexander passed (as Arrian and others repeatedly allege), or was founded also on some verbal confusion, cannot be stated. It was no doubt regarded (and perhaps not altogether untruly) as a part of a great alpine zone believed to traverse Asia from west to east, whether called Taurus, Caucasus or Imaus. Arrian himself applies Caucasus distinctly to the Himalaya also. The application of the name Tanais to the Syr seems to indicate a real confusion with Colchian Caucasus. Alexander, after building an Alexandria at its foot (probably at Hupian near Charikar), crossed into Bactria, first reaching Drapsaca, or Adrapsa. This has been interpreted as Anderab, in which case he probably crossed the Khawak Pass, but the identity is uncertain. The ancient Zend name is, according to Rawlinson, Paresina, the essential part of Paropamisus; this accounts for the great Asiastic _Parnassus_ of Aristotle, and the _Pho-lo-sin-a_ of Hsuan Tsang. The name Hindu Kush is used by Ibn Batuta, who crossed (c. 1332) from Anderab, and he gives the explanation of the name which, however doubtful, is still popular, as (Pers.) Hindu-Killer, "because of the number of Indian slaves who perished in passing" its snows. Baber always calls the range Hindu Kush, and the way in which he speaks of it shows clearly that it was a range that was meant, not a solitary pass or peak (according to modern local use, as alleged by Elphinstone and Burnes). Probably, however, the title was confined to the section from Khawak to Koh-i-Baba. The name has by some later Oriental writers been modified into Hindu _Koh_ (mountain), but this is factitious, and throws no more light on the origin of the title. The name seems to have become known to European geographers by the Oriental translations of the two Petis de la Croix, and was taken up by Delisle and D'Anville. Rennell and Elphinstone familiarized it. Burnes first crossed the range (1832). A British force was stationed at Bamian beyond it in 1840, with an outpost at Saighan. The Hindu Kush, formidable as it seems, and often as it has been the limit between petty states, has hardly ever been the boundary of a considerable power. Greeks, White Huns, Samanidae of Bokhara, Ghaznevides, Mongols, Timur and Timuridae, down to Saddozais and Barakzais, have ruled both sides of this great alpine chain.