By: Mir M.Hosseini
Units of Persian army passed the strait of Bosphorus near the area where Constantinople was built later. The expedition aimed to drive back Scythians from across the Danube river. Scythians were Arians who migrated from Central Asia. Some of them settled in Sekestan, the rest moved to southern Russia in the 8th-7th century BC. They were fierce warriors who established an empire from western Persia to Syria. Although they had been driven out of Anatolia by Medes, they still held territory near today's Ukraine.
Another arm of Iranian troops were passing The Marmara to join the main units headed by General Bogoas. Dariush The Great wanted to create an empire which was safe for residents to be able to deal with their day to day activities such as commerce and agriculture. Therefore, to further promote trade and communication along the greatest empire on earth, safe passages were needed. Scythians who were expert horsemen, made their living by plundering small cities and villages, thus created fear among residents. One of the Persian Empire's primary obligations towards nations who submitted was to provide their security against invasions.