Complex sentence: The monks and the ordinary priests remained, however, predominantly Bulgarian, thus allowing the archbishopric to preserve to a large extent its national character, to uphold the Slavonic liturgy and to continue its contribution to the development of the Bulgarian literature.
Split into simpler sentences: The monks and the ordinary priests remained, however, predominantly Bulgarian. To a large extent the archbishopric preserved its national character, upheld the Slavonic liturgy and continued its contribution to the development of Bulgarian literature.