The vast space of country comprised between the Indus on the east, the Oxus and Caspian Sea to the north, the Persian Gulf and Indian Ocean to the south, and the line of Mount Zagros to the west, appears to have been occupied in these times by a great variety of different tribes and people, yet all or most of them belonging to the religion of Zoroaster, and speaking dialects of the Zend language. It was known amongst its inhabitants by the common name of Iran or Aria: it is, in its central parts at least, a high, cold plateau, totally destitute of wood, and scantily supplied with water; much of it indeed is a salt and sandy desert, unsusceptible of culture. Parts of it are eminently fertile, where water can be procured and irrigation applied. Scattered masses of tolerably dense population thus grew up; but continuity of cultivation is not practicable, and in ancient times, as at present, a large proportion of the population of Iran seems to have consisted of wandering or nomadic tribes with their tents and cattle. The rich pastures, and the freshness of the summer climate, in the region of mountain and valley near Ekbatana, are extolled by modern travellers, just as they attracted the Great King in ancient times during the hot months. The more southerly province called Persis proper (Faristan) consists also in part of mountain land interspersed with valley and plain, abundantly watered, and ample in pasture, sloping gradually down to low grounds on the sea-coast which are hot and dry: the care bestowed both by Medes and Persians on the breeding of their horses was remarkable. There were doubtless material differences between different parts of the population of this vast plateau of Iran. Yet it seems that, along with their common language and religion, they had also something of a common character, which contrasted with the Indian population east of the Indus, the Assyrians west of Mount Zagros, and the Massagetae and other Nomads of the Caspian and the Sea of Aral--less brutish, restless and blood-thirsty than the latter--more fierce, contemptuous and extortionate, and less capable of sustained industry, than the two former. There can be little doubt, at the time of which we are now speaking, when the wealth and cultivation of Assyria were at their maximum, that Iran also was far better peopled than ever it has been since European observers have been able to survey it--especially the north-eastern portion, Bactria and Sogdiana--so that the invasions of the Nomads from Turkestan and Tartary, which have been so destructive at various intervals since the Mohammedan conquest, were before that period successfully kept back.