This is supposedly the oldest piece of writing, discovered at the Jiahu site in Henan, China. The excavations carried out in 1999 uncovered these symbols embedded in tortoise shells, suggesting that writing first started soon after the Neolithic Revolution, around 7000 – 5800 BCE in the Peiligang culture, long before its presumed origin on the cuneiform tablets of Mesopotamia (around 3200BCE) (Clair & Snyder, 2012).
It should be noted that these are just symbols; a form of proto-writing so there are debates about whether this pertained to any language at all as its meaning is undeciphered to date; but the symbols are related to the modern Chinese script than any other style of writing (Malone, 2012).So it is fair to say that this nevertheless is a representative of written communication; and quite possibly the oldest one.
Clair,K. & Snyder, C.B. (2012). A typographic Workbook: A Primer to History, Techniques, and Artistry. USA: John Wiley & Sons
Malone, M. S. (2012). The Guardian of All Things: The Epic Story of Huan Memory. USA: St. Martin’s Press