Carbon dating only
It takes another 5,730 for half of the remainder to decay, and then another 5,730 for half of what's left then to decay and so on.
The period of time that it takes for half of a sample to decay is called a "half-life." Radiocarbon oxidizes (that is, it combines with oxygen) and enters the biosphere through natural processes like breathing and eating.
Scientists have tried to extend confidence in the carbon dating method further back in time by calibrating the method using tree ring dating.
Unfortunately, tree ring dating is itself not entirely reliable, especially the "long chronology" employed to calibrate the carbon dating method.
Unfortunately the ratio of carbon-12 to carbon-14 has yet to reach a state of equilibrium in our atmosphere; there is more carbon-14 in the air today than there was thousands of years ago.