History of Latvia between 400 AD - 799 AD
During the so-called Era of the Barbarian Invasion (400—800 AD) did the Slavs begin to move northwards from the steppes of Southern Russia. This migration began under the pressure of the sub-Black Sea Goths and several Tartar-Turk tribes. The Slavs moved into the woodlands inhabited by some of the extreme Eastern Balt tribes. The total area inhabited by Balts at that time was very wide and covered White Ruthenia, extending deep into Central Russia as far as Tula and Chernigov, to the regions where the rivers Dnieper, Oka, Volga and Daugava have their sources.
Under the pressure of Eastern Slays (the Russians), one Balt tribe, the Latgali, moved down the River Daugava (Western Duna) and joined their kinsfolk in Latvia, gradually pressing the Estonians further north.
Reference: Latvians.com
Previous historical period: Roman Iron Age (0-399) | Next historical period: Viking Age (800-1149)The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.