"Universally accepted historical conclusion"

My comparison with ijmāʿ (scholarly consensus in Islamic jurisprudence) is interesting as an analogy, but they are not equivalent.

In Islamic legal theory, ijmāʿ can be treated as a binding source of law under certain schools of thought.

Historical consensus has a different status. It is provisional, not binding. Even a very strong consensus can change if new evidence, new methods, or more persuasive interpretations emerge. So the similarity is that both involve broad agreement among specialists; the difference is that historical consensus is always open to revision.