 While most sites aren't dated, the age ranges of dated sites is between the 2nd to 16th century CE.They are divided into two phases.The first is an older megalithic tradition associated with the Neolithic Austronesian rectangular axe culture (2,500 to 1,500 BCE); while the second is the 3rd or 4th century BCE megalithic tradition associated with the (non-Austronesian) Dong Son culture of Vietnam.