Tribonian's code ensured the survival of Roman law. It formed the basis of later Byzantine law, as expressed in the "Basilika" of Basil I and Leo VI the Wise. The only western province where the Justinianic code was introduced was Italy (after the conquest by the so-called Pragmatic Sanction of 554), from where it was to pass to Western Europe in the 12th century and become the basis of much European law code. It eventually passed to Eastern Europe where it appeared in Slavic editions, and it also passed on to Russia. It remains influential to this day.