The Byzantine Empire came from the roman empire but was very different. They had a capital of Constantinople and practiced eastern orthodox. They spoke Greek. The empire grew strong and lasted one thousand years.
Many byzantine ideas were introduced into Russia through trade. They learned the Cyrillic alphabet, religion, art work and architecture.
There was contributions to our society now such as Justinians code(the laws of the byzantine empire based on the ‘twelve tables’ of roman law, Became a basis for laws in many European nations). Also there art and architecture which was usually supported by the Christian church. One of the biggest contributions were that they preserved the Greek and roman culture.