The backbone or main water-divide of the Hindu Kush continues to form the boundary between Afghanistan and those semi-independent native states which fringe Kashmir in this mountain region, until it reaches Kafiristan.
South of Arnawai the Kunar valley becomes a part of Afghanistan (see Kunar).
At this time the Russians were advancing rapidly in Central Asia, and a Persian army, not without Russian support, was besieging Herat, the traditional bulwark of Afghanistan on the east.
In Afghanistan the Sayads have much of the commerce in their hands, as their holy character allows them to pass unharmed where other Pathans would be murdered.
The cold is then intense and the force of the wind cyclonic. Speaking generally, the Afghanistan climate is a dry one.
Every pass of importance is known and recorded; every route of significance has been explored and mapped; Afghanistan has assumed a new political entity by the demarcation of a boundary; the value of Herat and of the Pamirs as bases of aggression has been assessed, and the whole intervening space of mountain and plain thoroughly examined.
North of the railway line, hedged in between Afghanistan and the plains of the Indus, stretch the long ridges of rough but picturesque highlands, which embrace the central ranges of the Suliman system (the prehistoric home of the Pathan highlander), where vegetation is often alpine, and the climate clear and bracing and subject to no great extremes of temperature.
The highlands which shut off the Turkestan provinces from Southern Afghanistan have afforded the best opportunities for geological investigation, and as might be expected from their geographical position, the general result of the examination of exposed sections leads to the identification of geological affinity with Himalayan, Indian and Persian regions.
The chief river of Bokhara is the Oxus or Amu-darya, which separates it from Afghanistan on the south, and then flows along its south-west border.
Quercus Ilex, the evergreen oak of southern Europe, is found in forests as far east as the Sutlej, accompanied with other European forms. In the higher parts of Afghanistan and Persia Boraginaceae and thistles abound; gigantic Umbelliferae, such as Ferula, Galbanum, Dorema, Bubon, Peucedanum, Prangos, and others, also characterize the same districts, and some of them extend into Tibet.