Complex sentence: The stones were engraved in the Old Norse language with Scandinavian runes, and all of them are found in modern-day Sweden, the majority of which reside in Uppland (18 runestones) and Södermanland (7 runestones).
Split into simpler sentences: The stones were engraved in the Old Norse language with Scandinavian runes, and all of them are found in modern-day Sweden. The majority are found in Uppland (18 runestones) and Södermanland (7 runestones).