the failure of science, page-42

Science is a METHOD. Initially scientists put up an hypothesis and then run trials first to prove it and then to disprove it.

These tests have to be done by many of their peers until there is a general acceptance of the hypothesis. If then in the future someone disproves it, there will be a reassessment by the experts in the particular field of study.

The example you give of someone making up the history of Wales has no relevance to the above.

PS Two thousand years ago the Romans and Greeks were writing sophisticated literature. The earliest written texts date back about 2600 BC - in Mesopotamia and Egypt mainly.