The Ostrogoths were a branch of the Gothic tribes, known for their role in the migration period of Europe during the early Middle Ages. They originated in what is now modern-day Ukraine and later moved into Italy, where they established a kingdom in the 5th century under their king, Theodoric the Great. The Ostrogoths played a significant role in the decline of the Western Roman Empire. Their kingdom in Italy was marked by a blend of Roman and Gothic cultures, contributing to the region's political and social landscape until their defeat by the Byzantine Empire in the 6th century.