988-1240 CE
From 988 to 1240 CE, the Rusyns transformed from Viking traders and Slavic tribes into the mightiest Christian realm between Constantinople and the Rhine. Vladimir's baptism in the Dnieper brought Byzantine faith and Greek letters; Yaroslav the Wise built Saint Sophia and gave his daughters to the kings of Europe. Then the Mongol tide came, and golden-domed Kyiv burned, and the Rus' lands passed under the shadow of the khans.