Quite convincing dates are sometimes arrived at by importing parallels from other contemporaneous cultures.This parallelism is formed due to trade relations, particularly wehen trade followed in both directions.
For example, beads closely resembling those from the temple repositories at Cnoss and dating from C.1600 B.
C were found in a late context (Period V) at Harappa. By noting the association of these beads it has been possible to trace a archaeological datum line across Indian sub-continent and Mesopotamia.
At that time the radioactive disintegration takes over in an uncompensated manner. only half the C-14 will remain after the half-life period.
In the disintegration process the Carbon-14 returns to nitrogen emitting a beta particle in the process.
In such cases subjective element cannot be ruled out.