According to Skordelis, when Thracians were subjected by Alexander the Great they finally assimilated to Greek culture and became as Greek as Spartans and Athenians, although he considered the Thracian language as a form of Greek. According to Crampton (1997) most Thracians were eventually Hellenized or Romanized, with the last remnants surviving in remote areas until the 5th century. According to Marinov the Thracians were likely completely Romanized and Hellenized after the last contemporary references to them of the 6th century. This theory holds the Christianization of the Roman Empire as the main factor of immediate assimilation.