It was the eastern half of the old Roman Empire. The Byrantine Empire was compared with Roman Empire. The Roman capital was Roman. The Byrantine capital Constantinople. Roman religion was Roman Catholic (christian) while the Byrantine realigion was Eastern Orthodox. Roman language was Latin and Byrantine language was Greek. Roman was the western of the old Roman Empire, while Byzantine was the eastern half of the old Roman Empire. Roman fell into the "Dark Ages" while Byzantine lasted 100 years and grew strong.
The Byzantine Empire had a big impact on Russia. The Russia religion was Eastern Orthodox. It was also known has the Russian Orthodox. They had the Byzantine trade. The traded Cyrillic alphabet, religion, art work, and the architecture.
Now you might be wondering how did it last so long. Well, they had an organzied government. They didn't let the Empire get to big. They also minded their own business.
Some contributions to our society:
Justinian's code- The laws of the Byzantine Empire- based on the "Tweleve Tables" of the Roman law, became a basis for laws in many European nations.
Art and Architecture- Usually supported the christian Church.