Original: All of the show's music was composed by "The Track Team", which consists of Jeremy Zuckerman and Benjamin Wynn, who were known to Dante and Konietzko because Zuckerman was Konietzko's roommate.
Simplified: All of the show's music was written by "The Track Team", which consists of Jeremy Zuckerman and Benjamin Wynn, who were known to Dante and Konietzko because Zuckerman was Konietzko's roommate.