According to the article, they don’t start anything as complex as real history until 4th grade. They should be studying history years before that, IMO.
There aren’t that many years before that. 4th graders are only 10. I am sure they learn about George Washington, and Abraham Lincoln earlier, but most history is too complex to be taught much earlier. My kids learned state history in 3rd grade. By 4th grade they remember nothing about it.