Romanization was the process of acculturation, integration, and assimilation of other peoples and cultures into the Roman culture. Historically, Romanization occurred as the Roman Republic and Empire expanded its borders and incorporated new peoples. Assimilation occurred from the top down, with the Romans taking the sons of local rulers as hostages and raising them in the Roman culture. Rome's client rulers would adopt aspects of Roman culture, including adding Rome's Hellenic pagan gods to their religious pantheon and building statues of Julius Caesar. Eventually, the subject peoples themselves would adopt Roman culture, including the Latin language, styles of architecture (public baths), the emperor cult, gladiator fights, and dress fashions (togas and sandals, etc.). Romanization was highly successful in the west of the empire, notably in Gaul, where the Celtic cultures and languages eventually became extinct. In the Hellenized east, however, Greek culture only became more powerful, although Rome's eastern subjects saw themselves as Romans; this cultural distinction would lend the Eastern Roman Empire its own Greek nature, differentiating it from the predominantly-Latin Western Roman Empire. In North Africa, the Berbers of Mauretania were thorougly Romanized, and they would retain this Romanized culture until the Islamic conquest in the 7th century AD. Romanization has left a notable impact on modern Europe, with Spanish, French, Italian, Romanian, and Portuguese all originating from the Latin language.