Geographically, the country of Iran is located in West Asia and borders the Caspian Sea, Persian Gulf, and Gulf of Oman. Topographically, it is predominantly located on the Persian Plateau. Its mountains have impacted both the political and the economic history of the country for several centuries. The mountains enclose several broad basins, on which major agricultural and urban settlements are located. Until the 20th century, when major highways and railroads were constructed through the mountains to connect the population centers, these basins tended to be relatively isolated from one another.
Typically, one major town dominated each basin, and there were complex economic relationships between the town and the hundreds of villages that surrounded it. In the higher elevations of the mountains rimming the basins, tribally organized groups practiced transhumance, moving with their herds of sheep and goats between traditionally established summer and winter pastures. There are no major river systems in the country, and historically transportation was by means of caravans that followed routes traversing gaps and passes in the mountains. The mountains also impeded easy access to the Persian Gulf and the Caspian Sea.
With an area of , Iran ranks seventeenth in size among the countries of the world. Iran shares its northern borders with several post-Soviet states: Armenia, Azerbaijan, and Turkmenistan. These borders extend for more than , including nearly of water along the southern shore of the Caspian Sea. Iran's western borders are with Turkey in the north and Iraq in the south, terminating at the Arvand Rud.
The Persian Gulf and Gulf of Oman littorals form the entire southern border. To the east lie Afghanistan on the north and Pakistan on the far south. Iran's diagonal distance from Azerbaijan in the northwest to Sistan and Baluchestan Province in the southeast is approximately .
List of mountains in IranList of islands of IranTransport in Iran and Communications in Iran
The topography of Iran consists of rugged, mountainous rims surrounding high interior basins.