A root vegetable with a bark-like, brown exterior and a starchy interior that can be compared to a russet potato. 

Asia and Africa.

Yams were introduced to the New World in the 16th century, with African people who were enslaved and forcibly migrated. 

In the United States, sweet potatoes are also known as yams and vice versa. In the 1930s, Louisiana sweet potato growers started calling their crops “yams” in an attempt to distinguish their sweet potatoes from others on the market. See Sweet Potato for more information. 

New Oxford Book of Food Plants by John Vaughan et al. (2009)

“What’s the Difference Between a Sweet Potato and a Yam?” by Alyse Whitney (2017)

https://www.bonappetit.com/story/difference-between-sweet-potato-and-yam