to the TEXAS flag.
Just pointing out that the educational experience in Texas is not necessarily indicative of what the educational experience in the rest of the US is like.
I remember this controversy from a while and IIRC I don't think this is accurate. For one thing, they teach that slavery was a central role. https://www.npr.org/2018/11/16/668557179/texas-students-will...
I remember looking at the actual key points in the Texas curriculum and nothing seems that unusual. Some people we IMO nitpicking.
There's a great difference of scale.
Lincoln died about 150 years ago. There are voluminous primary sources about Lincoln - e.g. photographs of him, original documents that he wrote, firsthand accounts of his actions, etc. We certainly don't know every detail of his life, but we do know a lot of it, and we're quite confident it's true.
The Tang dynasty, by contrast, fell over a thousand years ago. We know of it primarily through second- and third-hand histories and through interpretation of archaeological artifacts - much like our knowledge of Greek and Roman history, for instance. There are a lot of thinly covered areas, and many of the sources are biased; there's a lot more to be uncertain about.