If but little had been hitherto known of the northern slopes of the Great Atlas from the reports of the few travellers who had viewed the range from the low country, or attained its outer slopes, the southern side of the main chain remained a sealed book to geographers, whose reliance on the vague reports of native informants has led them, like the chartographers of the middle ages, to fill up the blank space on their maps by representations utterly discordant and contradictory. Ever since we had been in South Marocco, we had heard of the Sous valley, as the proper home of everything strange and marvellous to be found in the empire. It is there, our informants assured us, that lions and other savage beasts roam at leisure, there pythons twenty or even thirty feet long lie in wait for the traveller, mines of the precious metals abound in Sous, and in Sous the soil is so fertile that all the products of nature are obtained without labour. But of the physical features of the country we could learn nothing. Whether it were enclosed on the southern side by a second lofty range, or Anti-Atlas, parallel to that we already knew, or merely by secondary branches diverging from the main chain, and from how far eastward the sources of the Sous might flow, were all matters quite unknown to us. One European, indeed, had traversed some part of the valley, and should have been able to throw some little light on these obscure points; but unfortunately the few lines in which Gerhard Rohlfs recounts his adventurous journey to Tarudant, and thence eastward to the northern skirts of the Sahara, give scarcely any information. He speaks of high mountains lying south of the Sous valley, but says nothing to show what relation these bear to the main chain. It appears from his account, that no considerable ascent is necessary in order to pass from the southern branch of the Sous to the streams that flow southward towards the Great Desert; but whether the Great Atlas and the Anti-Atlas are throughout their length separated by a broad trough, in the same way as Lebanon and Anti-Lebanon, or Anti-Atlas be a diverging range over which Rohlfs made his way by a deep pass or depression, it is impossible to infer from his narrative.