Interesting fun fact. You know the story of how Christopher Columbus sailed to prove the Earth was round? That's entirely false! In fact people never really thought the Earth was flat. In ancient Greece Eratosthenes calculated the CIRCUMFERENCE of the Earth.
Most Europeans agreed the Earth was round. What was disputed was what the circumference of the Earth was. Eratosthenes was accurate to within a few hundred miles, thousands of years before NASA got it down to the inch. It wasn't known that Eratosthene was correct until much later. There were many wildly different estimates of the Earth's circumference. Colombus thought the Earth was much smaller and therefore it would feasible to sail west and reach the East Indies. Few people thought Colombus would sail off the edge of the world, but many people thought he would run out of food sailing across a big empty ocean.
He was also under the impression that the Earth was shaped like a pear, presumably courtesy of a Dante's Christian fanfic, The Divine Comedy.
Did they specify WHICH world? Perhaps they were predicting the end of the Old World in the End Times...