Social media has been buzzing since Donald Trump said Korea “used to be a part of China” after a visit with China’s leader. The twitterati have offered to help the US president with his world history, while South Korea wants to know who said what to whom.

Trump made the controversial remark in an interview with the Wall Street Journal back on April 12.

However, social media users have only recently begun to pay attention to that particular remark.When the president was describing his much-anticipated meeting with China’s leader, Xi Jinping, which had taken place earlier in April, he noted that the two had “very good chemistry.”

.@FLOTUS & I are honored to welcome the President of the People's Republic of China, Xi Jinping, & Madame Peng Liyuan to the United States. pic.twitter.com/n6ZX4AySNH — President Trump (@POTUS) April 7, 2017

Apparently, at some point, their conversation had touched on the history of China.“He [Xi] then went into the history of China and Korea. Not North Korea, Korea. And you know, you’re talking about thousands of years… and many wars. And Korea actually used to be a part of China. And after listening for 10 minutes, I realized that not – it’s not so easy,” said Trump.

Social media was completely stunned by the comment.

Every day is a school day. Trump accused of 'shocking ignorance' - repeats Chinese claim Korea was 'part of China' https://t.co/8xlziCSDbK — Robert M (@3drm) April 20, 2017

Some couldn’t hold back their emotions and added scores of emojis to their comments.

Donald Trump accused of 'shocking ignorance' as he repeats Chinese claim that Korea was 'part of China' 😂😂😂😂😂this is best comedy show ever — mukraja (@mukraja) April 20, 2017

"Korea actually used to be a part of China."- Donald Trump



😭😂😭😂😭😂😭 — Mebenie Ngai (@mebeniengai416) April 20, 2017

One person even ironically offered to help Trump to study world history in depth.

@TelegraphNews I can help Don with world history class... — Psychoanalyst (@psychoanalyst3) April 20, 2017

@washingtonpost Guess he missed those history classes in high school and college. Or old age is setting in and the memory has declined. — Jim C (@jim3611) April 20, 2017

Some people wondered on what grounds Trump had made such a statement.

@nktpnd I'm sure you saw Trump's version of China/Korea history. Topic for the Diplomat podcast? https://t.co/7MtincDqKg — Patrick Moore (@PatrickDallas) April 20, 2017

@washingtonpost In case anyone else has forgotten, our former President was a Harvard Graduate. It's now clear why @realDonaldTrump loves the undereducated — Paayal Priyaanka (@PaayalPriyaanka) April 20, 2017

Or if Korea had belonged to China on the day God created Earth?

@washingtonpost Yes, it was on that first day that God created Earth. — G Bart Billbrough (@gbartb) April 20, 2017

People speculated on whether there were books on the topic that said Korea had, indeed, been part of China.

Now that Trump is so interested in Korea ("once a part of China"), we might point out that there are, actually, "books" on the topic.... — Ari Costello (@AriCostello) April 20, 2017

Other wondered if Trump could even find Korea on the map.

@washingtonpost Fact check, I truly believe that the President can't find Korea on a map. #notthebrightestbulb — Nancy Shapiro (@nancybknits) April 20, 2017

@washingtonpost I googled it. You all should too before you comment. Still it is now, not then. We know we only have this planet to live on. — eleanor sparling (@rastabbmama) April 20, 2017

Sarcasm and irony prompted people on Twitter to invent other fantasy versions of world history.Like one in which, Scotland had always been a part of the UK:

@TelegraphNews Like saying Scotland has always been part of the UK. — Thomas Venour (@VenourThomas) April 20, 2017

or Iraq a province of Syria.

@washingtonpost and Iraq is actually Syria — YKD (@suburbanite005) April 20, 2017

@washingtonpost Dey dude potus , yes of course, the same as parts of USA belongs to Canada and Mexico . You got that stupid ? — Leo Antony (@leo_philo) April 20, 2017

@qz He probably meant Vietnam or Indonesia — David Burrows (@dmburrows) April 18, 2017

In the meantime, some did take the remark seriously, saying that they, personally, and America, as a whole, were embarrassed by this new controversial statement coming from the US president.

Stop embarrassing us & yourslf.

Trump’s claim that Korea ‘actually used to be a part of China’ - The Washington Posthttps://t.co/YExAVVR0BJ — glenda madden (@GlendaMadden) April 20, 2017

Analysis | Trump's claim that Korea 'actually used to be a part of China' https://t.co/gnbsaUHc65 Such an ignorant embarrassment! — Lori Lee (@rbmumsie) April 20, 2017

Trump: Korea used to be a part of China. He's killing me. https://t.co/rJ9PgavHcD — Ihave2no (@Ihave2no) April 20, 2017

@washingtonpost Ugh it just keeps getting worse. Utter embarrassment! — Dannean Altman (@AltmanDannean) April 19, 2017

@washingtonpost How embarassing that we have this fool sitting in the chair of @POTUS and even sadder that #MAGA@GOP values the lack of facts and knowledge — Brian Sweet (@SweetINXS) April 20, 2017

On Wednesday, the Washington Post published its own historical analysis of China-Korea relations since the first century.

Trump’s remarks didn’t go unnoticed in the South Korean media. On Thursday, the country’s Foreign Ministry said it is checking whether China’s president really did tell Trump that Korea was once a part of China.

“We are working to confirm the reports through diverse diplomatic channels including the United States and China,” South Korean Foreign Ministry spokesman Cho June-hyuck said, as cited by Yonhap news agency. “As soon as detailed facts are confirmed, [the government] will make the necessary response,” he said.

On Wednesday, a South Korean Foreign Ministry source said that Trump’s remark was historically untrue.

“Whether that is true or not, Korea hasn’t been a part of China for thousands of years, and it is an historical fact that the international community acknowledges and no one can deny it,” a Foreign Ministry official told Yonhap on the condition of anonymity.