When did yams emerge in history and how are they grown?

Answer 1

the south americans(native to peru) grew sweet potatoes but the true yam, is from africa. they are totally different plants. the slave traders brought the yam from africa to feed the slaves, so they would have some familiar food.
dioscorea rotunda(white yam) and dioscorea cajenensis(yellow yam) are native to africa.
ipomeoa batatas (sweet potato)

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