In his advance toward the dominions of Croesus in Asia Minor, Cyrus had passed to the northward of the great and celebrated city of Babylon. Babylon was on the Euphrates, toward the southern part of Asia. It was the capital of a large and very fertile region, which extended on both sides of the Euphrates toward the Persian Gulf. The limits of the country, however, which was subject to Babylon, varied very much at different times, as they were extended or contracted by revolutions and wars. The River Euphrates was the great source of fertility for the whole region through which it flowed. The country watered by this river was very densely populated, and the inhabitants were industrious and peaceable, cultivating their land, and living quietly and happily on its fruits. The surface was intersected with canals, which the people had made for conveying the water of the river over the land for the purpose of irrigating it. Some of these canals were navigable. There was one great trunk which passed from the Euphrates to the Tigris, supplying many minor canals by the way, that was navigable for vessels of considerable burden. The traffic of the country was, however, mainly conducted by means of boats of moderate size, the construction of which seemed to Herodotus very curious and remarkable. The city was enormously large, and required immense supplies of food, which were brought down in these boats from the agricultural country above. The boats were made in the following manner: first a frame was built, of the shape of the intended boat, broad and shallow, and with the stem and stern of the same form. This frame was made of willows, like a basket, and, when finished, was covered with a sheathing of skins. A layer of reeds was then spread over the bottom of the boat to protect the frame, and to distribute evenly the pressure of the cargo. The boat, thus finished, was laden with the produce of the country, and was then floated down the river to Babylon. In this navigation the boatmen were careful to protect the leather sheathing from injury by avoiding all contact with rocks, or even with the gravel of the shores. They kept their craft in the middle of the stream by means of two oars, or, rather, an oar and a paddle, which were worked, the first at the bows, and the second at the stern. The advance of the boat was in some measure accelerated by these boatmen, though their main function was to steer their vessel by keeping it out of eddies and away from projecting points of land, and directing its course to those parts of the stream where the current was swiftest, and where it would consequently be borne forward most rapidly to its destination.