Why did historians refer to the lost years?

Historians refer to the "lost years" primarily in the context of the life of William Shakespeare, specifically the period between 1585 and 1592, for which there is little documented evidence about his activities. This gap in records has led to much speculation about his life, influences, and the development of his writing. The term highlights the mystery surrounding this phase and the challenges historians face in reconstructing a complete narrative of his life and career.