The road next hugs the Hari Rud, and, passing the high-walled town of Zindajan to the south, runs, white and even and hard, with the scarlet and purple of poppies and thistles fringing it, between long gravel slopes of open dasht and the twin-peaked ridge of Doshak, to Rozanak and Kuhsan. Kuhsan is a little to the south of the Kaman-i-Bihist. It was here that the British Commission of the Russo-Afghan Boundary gathered in the late autumn of 1884, one half from England and the other half from India. The drab squares of the cultivated plain were bare then, in November, and the poplars on the banks of the river were scattering yellow leaves to the blasts of the bitter north-west winds of autumn which sweep through Khorasan and Seistan, making of life a daily burden. But there came a marvellous change in the spring-time, when the world was scarlet and green below and blue above; when the sand-grouse began to chatter through the clear sky; then Kaman-i-Bihist (the bow of Paradise) justified its name. The old Arab of the trading days who wandered northward to Sarakhs must have loved this place. Stretching Sarakhs-ward are the hills, rocky and broken along the river edge, but gradually giving place eastward to easy rounded slopes, softened by rain and snow, and washed into smooth spurs with treacherous waterways between which become quagmires under the influence of a north-western "shamshir." The extraordinary effect of denudation which yearly results from the heavy rain-storms which are so frequent in spring and early summer in these hills must have absolutely changed their outlines during the centuries which have elapsed since the Semitic trader trod them. A summer storm-cloud charged with electricity may burst on their summits, and the whole surface of the slopes at once becomes soft and pulpy. Mud avalanches start on the steeper grades and carry down thousands of tons of slimy detritus in a crawling mass, and spread it out in fans at their feet. It is not safe to say that the modern passes of the Paropamisus north of Herat--the Ardewan and the Babar--were the passes of mediæval commerce, although the Ardewan is marked by certain wells and ruined caravanserais which show that it has long been used. It seems possible that these passes may have shifted their positions more than once. There was undoubtedly a well-trodden route from Bousik, which carried the traveller more directly to Sarakhs than would the Ardewan or even the Chashma Sabz Pass. This road followed the river more closely than any railway ever will. It turned the river gorge to the east, and probably passed through the hills by the Karez Ilias route, which runs almost due north to Sarakhs. The only certain indication which we can find in Idrisi is the statement that the "silver hill" (_i.e._ the hill of the silver mine) is on the road from Herat to Sarakhs. The Simkoh (silver hill) is still a well-known feature in the broken range of the Paropamisus, near that route.