Complex sentence: Their subordinates and the people followed them and borrowed a major part of the East Slavic versions of Christian names in the 11th-12th centuries, that became increasingly widespread among the pagan population in Aukštaitija, and much less in Samogitia.
Split into simpler sentences: Their subordinates and the people followed their example, borrowing, for instance, many of the East Slavic versions of Christian names in the 11th-12th centuries. This borrowing became increasingly widespread among the pagan population in Aukštaitija, though much less in Samogitia.