There are dozen different materials that can be used in dating, not just only carbon. On geological features, there can be K-Ar dating for minerals millions years old. Carbon dating is rather accurate to 45,000 years or approximately 8 half times. Other methods like Ionimum-thorium-232 dating is widely used in sediments with halflife of 75,000 years. Besides radiometric dating, there are other methods like pollen, sediment, electromagnetic dating.
One important feature for dating the age of the early settlements is glaciation which retracted and repeated the process for period of several hundred thousands years. There was a brief period of warm-up in 25000 years ago followed by rapid glaciation in Europe, Asia, and Northern America, which ended around 10,000 BC. This glaciation period is very easy to spot in terrain, sediments, flora, fauna, and elsewhere, and can determine population migration before the last Ice Age and interglacial period.