Simplify the following text for a Grade 7 native English-speaking person.
Original: Starting from Jamsil Arena in Seoul in May 2006 , they had concerts in major Korean cities like Busan , Daegu , Junju , and Kwangju .
Simplified: Starting from Jamsil Arena in Seoul in May 2006 , they held concerts in Busan , Daegu , Junju , and Kwangju .