Complex sentence: When the partnership ended, one of the two manufacturers became the manager of the silk factory until his death in 1446 or 1447; the silkshop endured until 1480, when the last descendant of that partner died.
Split into simpler sentences: When the partnership ended, one of the two manufacturers became the manager of the silk factory until his death in 1446 or 1447. The silk shop endured until 1480, when the last descendant of that partner died.