古代世界，或者古代史一词，用法相当模糊。

其所指称的历史时期依各文明发展情况快慢而有所不同，但就其上限而言，一般是以文本的出现作为古代史与史前史的分界。

Ancient history is the aggregate of past events from the beginning of recorded human history and extending as far as the Early Middle Ages or the Postclassical Era. The span of recorded history is roughly 5,000 years, beginning with Sumerian Cuneiform script, the oldest discovered form of coherent writing from the protoliterate period around the 30th century BC.