Archeologists estimate that humans began using cave drawings to communicate events in their lives as early as 40,000 years ago, a true system of writing didn’t emerge until around 3500 BC when civilizations in and around Mesopotamia began to develop one. More than 5,000 years later, plenty of clay tablets still survive as the oldest verified evidence of a writing system. While the Tărtăria tablets – uncovered in 1961 in a Romanian village – date back to 5500 BC, contain something that appears to be script, there has been no confirmation that it’s an organized style of writing.