* Definition of "school" is subjective: What constitutes a "school" varies. Was it a single teacher instructing a small group? A larger, more organized institution? The criteria are blurry.
* Lack of written records: Early forms of education likely relied on oral traditions and didn't leave behind easily interpretable records.
* Gradual evolution: Education didn't suddenly appear; it developed slowly, from apprenticeships and family instruction to more structured settings.
Some argue for ancient Mesopotamian scribal schools (around 3000 BCE) or similar institutions in ancient Egypt as early examples. However, these were specialized schools for a select few, not universal education as we understand it today. It's more accurate to say that formal schooling developed gradually across different cultures and time periods.