The great system of mountains which runs eastward through the heart of the continent—the Caucasus, the ranges of northern Persia, the Hindu Kush, the Himalayas—was well known to the Greek geographers, and the men of our time had acquired some hazy notions about it through reading Orosius and Isidore.[1253] Gervase of Tilbury,[1254] copying Orosius,[1255] tells how the Caucasus, joined by the “Imabus” (Imaus), divides India from Scythia and extends the entire length of Asia as far east as the Seric Ocean, though bearing different names in its eastern parts. Several of the maps show a straight range of mountains running east and west across the continent and labeled with various names (Taurus, Caucasus, Ceraunius, Paropamisus).[1256] The Jerome map[1257] reveals, on the other hand, many mountains in Asia but does not make them continuous. According to the _De imagine mundi_, the Caucasus divides the countries of southern from those of northern Asia. Among the former were India, Parthia, Mesopotamia, and Palestine, reaching in a straight line from the Far East to the Mediterranean.[1258] Egypt, which was regarded as belonging to Asia by the Greek geographers and by Isidore, was held to adjoin Palestine on the west, and to be part of this southern tier of countries. North of the Caucasus were the lands of the Seres, Bactria, Hyrcania, and Scythia, in the east, and in western Asia, Armenia, the country of Mount Ararat, Cappadocia (“where mares conceive through the wind alone and give birth to foals that live only three years”), and finally Asia Minor, almost completely surrounded by the sea.[1259] THE LAND OF THE “SERES”