Simplify the following text for a Grade 7 native English-speaking person.
Original: Blakey and Silver recorded together on several occasions , including the album A Night at Birdland ( 1954 , BN ) , having formed in 1953 a cooperative group with Hank Mobley and Kenny Dorham , retaining the name Jazz Messengers . By 1956 Silver had left and the leadership of this important band passed to Blakey , and he remained associated with it until his death .
Simplified: Blakey and Silver recorded together several times , like the album A Night at Birdland in 1954 .