The Persian Gulf.
The geography remained the same - continents did not move and mountains and rivers went on unheeding. Politically, Alexander simply took over the Persian Empire and converted it into an empire of his own.
Most of the northern borders of the empire in Europe were marked by the rivers Rhine and Danube. Dacia (Romania) was a Roman province beyond the Danube, but it was also given up by Aurelian between 271 and 275 due to continuous attacks from outside . The Romans had lands beyond the Rhine in Germany, but they were given up in 340-341 by Constans for the same reasons. Thus, eventually these two rivers became the whole of the northern frontier. The source of the Danube is close to the Rhine The above only takes continental Europe into consideration. However the Roman empire extended much further north into Scotland. There were rivers there and the Romans had marching camps as far north a the Firth of Clyde and the Clyde river and even further up to the Amrick river.
Rhine and Danube Rivers.
No rivers divided the western part of the Roman empire. If you mean what rivers formed the frontiers of the this part of the Roman Empire, they were the Rhine and the upper Danube. In between them there was the limes germanicus, a line of fortifications which crossed southern and central Germany.
Tigris and Euphrates Rivers.
The Persian Empire had access to several bodies of water, including the Persian Gulf to the south, the Caspian Sea to the north, the Mediterranean Sea to the west, and various rivers such as the Tigris and Euphrates in Mesopotamia. These bodies of water played a significant role in trade, transportation, and agriculture within the empire.
The Danube River and the Rhine River form the border of much of the northeastern part of the Roman Empire. These rivers provided natural barriers that helped protect the Empire from invasions from various tribes and armies.
In the Fertile Crescent and Egypt it was irrigated by the rivers. In the remaining areas it was mostly dry-farrming.
By boat on rivers, lakes and seas. By foot. By riding animals. By wheeled carts drawn by animals.
The Tigris River is further east than the Euphrates River.
I'm wanting to know the same thing!
Libya in the west, the Mediterranean Sea, the Arabian desert, the Black and Caspian Seas, the Syr Daria and Indus Rivers
The Tigris and Euphrates rivers flow into the Persian gulf
The Tigris River and the Euphrates River flow through Iraq and then meet near the city of Al Basrah to create the Shatt Al Arab River. See this map for a visual explanation: http://www.astreetjournalist.com/wp-content/uploads/iraq-map.gif1.bmp
Shatt al Arab
I assume it's because the former emperor Augustus died and the other emperor was content with the border.