What to increase the slave trade in africa during the seventh century? the crusades and holy wars. the establishment of trade networks between africa and portugal. the spread of islam into africa. an increase in trade between europe and asia.

What was zheng he’s most important accomplishment? zheng he spread chinese ideas and brought wealth to china from his travels. zheng he commanded an impressive fleet of ships. zheng he sailed the indian ocean and around africa. zheng he conquered lands as far away as africa to increase the dynasty’s power.