And their writings have to survive. Look at Mesopotamia, where writing began with cuneiform impressions in clay. We've got lots of clay tablets because those s

And their writings have to survive. Look at Mesopotamia, where writing began with cuneiform impressions in clay. We've got lots of clay tablets because those survive well when buried. When Imperial Aramaic written on parchment began to supplant Akkadian cuneiform, we lose a lot of the written record. It's created an odd situation where the written documentation of the second millennium BCE is often better than the first millennium BCE.