Complex sentence: Despite occasional spontaneous episodes of pogroms and killings, as during the Black Death, Poland was a relatively tolerant home for the Jews in the medieval period, by the mid- 16th century containing 80% of the world's Jewish population.
Split into simpler sentences: Despite occasional spontaneous episodes of pogroms and killings, as during the Black Death, Poland was a relatively tolerant home for the Jews in the medieval period. By the mid- 16th century, Poland was home to 80% of the world's Jewish population.