This is a picture of a traditional big band. The front row is saxes, the second trombones, and the third trumpets. On the side is the rhythm section.http://www.yankeehomecoming.com/Day4.html

Tommy Dorsey had his own big band as seen on the previous brass quintet or larger ensembles like symphony orchestras .  Sometimes Tommy Dorsey combined different types of groups to make a new sound, for example sometimes he included more string instruments in his band.

A traditional jazz band includes

5 saxophones

4 trombones

5 trumpets

1 piano

1 guitar

1 bass

1 drum set