Complex sentence: As the Viking invasions ceased in the middle of the 11th century, liturgical drama spread from Russia to Scandinavia to Italy; only in Muslim-occupied Spain were they not presented at all.
Split into simpler sentences: As the Viking invasions ceased in the middle of the 11th century, liturgical drama had spread from Russia to Scandinavia to Italy. Only in Muslim-occupied Spain were liturgical dramas not presented at all.