Complex sentence: At the time of the Black Death, English textile industries accounted for about 10% of English wool production; the English textile trade grew during the 15th century, to the point where export of wool was discouraged.
Split into simpler sentences: At the time of the Black Death, English textile industries accounted for about 10% of English wool production. The English textile trade grew during the 15th century, to the point where export of wool was discouraged.