John, or Ioannis (Ἰωάννης), Tzimiskes (Τζιμισκής) was a Byzantine and Eastern Roman emperor of the 10th century. "Tzimiskes" supposedly derives from an Armenian word (Չմշկիկ) meaning "red-booted" or short. He is likely of Greek and Armenian origin. He is known for his military prowess which enabled him to expand the Byzantine borders to include Thrace from fighting the Rus led by Sviatoslav in the Battles of Arcadiopolis and Dorostopol and Syria and Mesopotamia from fighting the Fatimid Caliphate. He is remembered as one of the best and most successful emperors.