Complex sentence: While in operation, NWA Wildside was one of the main affiliates of the National Wrestling Alliance, a group that dates back to 1948 and was one of the most-watched independent promotions in the United States.
Split into simpler sentences: While in operation, NWA Wildside was one of the main affiliates of the National Wrestling Alliance, a group that dates back to 1948. It was one of the most-watched independent promotions in the United States.