Such to the eye of an ordinary traveller, in search of the picturesque, was the aspect of the city and its environs at the time when the army of Mahomed Shah was marching upon Herat. To the mind of the military observer both the position and construction of the place were suggestive of much interesting speculation. Situated at that point of the great mountain-range which alone presents facilities to the transport of a train of heavy artillery, Herat has, with no impropriety of designation, been described as the “Gate of India.” Within the limits of the Heratee territory all the great roads leading on India converge. At other points, between Herat and Caubul, a body of troops unencumbered with guns, or having only a light field artillery, might make good its passage, if not actively opposed, across the stupendous mountain-ranges of the Hindoo-Koosh; but it is only by the Herat route that a really formidable well-equipped army could make its way upon the Indian frontier from the regions on the north-west. Both the nature and the resources of the country are such as to favour the success of the invader. All the materials necessary for the organisation of a great army, and the formation of his dépôts, are to be found in the neighbourhood of Herat. The extraordinary fertility of the plain has fairly entitled it to be called the “Granary of Central Asia.” Its mines supply lead, iron, and sulphur; the surface of the country, in almost every direction, is laden with saltpetre; the willow and poplar trees, which furnish the best charcoal, flourish in all parts of the country; whilst from the population might at any time be drawn hardy and docile soldiers to recruit the ranks of an invading army.[139] Upon the possession of such country would depend, in no small measure, the success of operations undertaken for the invasion or the defence of Hindostan.