Complex sentence: By the start of the 17th Century Neo-Confucianism had surplanted all other models for the Korean nation-state such that, without outside opposition, Neo-Confucian thought experienced first a split between Westerners and Easterners and again, between Southerners and Northerners.
Split into simpler sentences: By the start of the 17th Century Neo-Confucianism had surplanted all other models for the Korean nation-state. Without outside opposition however, Neo-Confucian thought experienced first a split between Westerners and Easterners and again, between Southerners and Northerners.