Complex sentence: In 1960 at age 22, she became the leader of the Nashville sit-ins, which lasted from February to May 1960, and which led to the desegregation of the cities lunch counters.
Split into simpler sentences: In 1960 at age 22, she became the leader of the Nashville sit-ins. The Nashville sit-ins lasted from February to May 1960, and led to the desegregation of the cities lunch counters.