Complex sentence: Although, Shinhwa was mostly on hiatus throughout 2005, they released two popular singles, "How Do I Say" and "Hey Dude!" and held the "Tropical Summer Story Festival" concert.
Split into simpler sentences: Although, Shinhwa was mostly on hiatus throughout 2005, they released two popular singles, "How Do I Say" and "Hey Dude!". They also held the "Tropical Summer Story Festival" concert.