Complex sentence: Prior to the great split between the Soviet Union and China in the early 1960s, Kim visited both capitals often, but the split created enormous problems for Kim, who struggled to keep on good terms with both of them.
Split into simpler sentences: Prior to the great split between the Soviet Union and China in the early 1960s, Kim visited both capitals often. The split created enormous problems for Kim, who struggled to keep on good terms with both of them.