Complex sentence: After the Nation disbanded, The Rock referred to himself as the "People's Champion", which led to Vince McMahon and the Corporation to target him since they had a problem with the people, they had a problem with the "People's Champion".
Split into simpler sentences: After the Nation disbanded, The Rock referred to himself as the "People's Champion", which led to Vince McMahon and the Corporation to target him. Since they had a problem with the people, they had a problem with the "People's Champion".