The trouble with history as a subject (or discipline, if you prefer) is that there are two aspects:

a) This what happened

b) This is why it happened

a) is stable, most of the time, we have the records, expect with very ancient history as archaeologists keep discovering new things that revise our ideas of what our ancestors could and did achieve.

b) is changeable, as we delve ever deeper into sources, as new ones become available. The facts stay facts, but different sources cast them in a different light. When I was young, we knew almost nothing about the Silk Road, but we were aware of the impact it had on European culture - we knew the what, but not the why.

So when teaching history, we have to carefully consider at what stage we move from teaching purely a) and introduce some b). In the UK, a) was taught almost exclusively up to 16. Those who stayed on for A-levels and dd history got more b) in preparation for university, where it was assumed you knew all the a) you needed and the whole thing was about b).