"Kanye is a dangerous caricature of a 'freethinking' black person in America," Sanders tweeted. "Frankly, I am disgusted and I'm over it. Also (I can't believe I have to say this): Slavery was far from a choice." Others put it more briefly.
"Slavery wasn't a choice," Russ Bengtson tweeted, "but listening to Kanye is."
Director Spike Lee accused West of making "uneducated comments" and urged him to "WAKE UP".
Lee wrote: "SLAVERY... A CHOICE??? My Brother, OUR ancestors did not choose to be stolen from mother Africa. OUR ancestors did not choose to be ripped of our religion, language, culture.
"OUR ancestors did not choose to be murdered, lynched, castrated, raped, burnt at the stake, families sold apart. OUR ancestors built this country (on land stolen from the Native Americans) from the ground up under the institution of SLAVERY."
On Twitter, musician Talib Kweli, wrote: "I will always have love for @kanyewest but bro out here putting targets on our backs. Slavery was not a choice."
Others used humour to make pertinent points under the hashtag #SlaveryWasAChoice, which was soon trending globally.
Many have used the hashtag to create fictitious scenarios, where enslaved African-Americans were working on plantations out of their own free will.
It comes as musician Will.i.am, a one-time friend of West, lashed out at the superstar over his slavery comments.
Appearing on Good Morning Britain, the star said that West had "thrown his ancestors under the bus" and was "ignorant".
An emotional Will.i.am told Piers Morgan he "wanted to cry" over West's remarks and believed that the comments were made merely as a marketing tool to promote his music and his Yeezy fashion line.
"That broke my heart ... my grandmother's grandma, who was a slave. And when you're a slave, you're owned. You don't choose if you're owned. When you're a slave you're deprived of education. That's not choice, that's by force ..." Will.i.am said.
He also pointed to the upcoming release of West's new album. "I hope it's not to raise awareness so you could sell some records and some shoes, because that would be the worst thing to do, to stir up this very touchy race situation and you be the benefactor from it," he said.
"So I encourage you, if you really believe this, give your shoes away for free, give your album away for free."
Describing West as "ignorant", the star said: "So I understand the need to have free thought, but if your thoughts aren't researched, that is just going to hurt those that are still in conditions where it's not choice ...
"That when they go down the street and there's a liqueur store and fast-food restaurants and your education is not being funded the same way that it is being in Calabasas, when governments stifle and limit the amount of money that goes to Chicago, Bronx, Watts, 5th Ward Mississippi, East Los Angeles, where I'm from."
"That statement was one of the most ignorant statements that anybody who came from the hood could ever say about their ancestors, that slavery is a choice. What are you talking about?"
