The identical ancestors point is the most recent point in history in which all existing humans were ancestors of everyone alive today. The IAP is, necessarily, quite some time before the time when the Most Recent Common Ancestor existed, and also quite some time after the time when Mitrochondrial Eve and Y-Chromosomal Adam lived.
Models based on realistic migration and interbreeding assumptions tend to produce quite recent IAPs.
This paper by Douglas L. T. Rohde of MIT estimates the mostly likely range for the IAP is 5000 to 15000 years. http://tedlab.mit.edu/~dr/Papers/Rohde-MRCA-two.pdf
At first blush this appears counter-intuitive since the amount of phenotypic variation between humans as we see them now appears to be much greater than could have occurred in 5 to 15 ky. Putting it simply, the racial diversity on Earth can’t have come into existence in such a brief time, and there’s palaeontological and archaeological evidence to suggest that the major racial differences existed more than 25000 years ago.
So how can it be that, for instance, a Han Chinese person, an Aboriginal person from the Kimberley area, and a Khoisan person from the Kalahari desert, could all have the same set of ancestors only a few thousand years back?
The answer is that although a modern individual is descended from all people alive at the IAP, not all of those IAP folk make the same contribution, and the specific genes they “donate” will differ from one modern person to another.
To explain by example: let’s take the middle estimate of 10000 years to the IAP. Suppose that there were 5 million people alive 10000 years ago.
The Han Chinese person above had two parents, four grandparents and so on. Going back 10000 years takes us back 400 generations. If I were to draw his family tree back to that generation, I would find 2 to the power of 10000 places in the tree. That is, about 3 times 10^120, or 3000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000, about three thousand billion billion billion billion billion billion billion billion billion billion billion billion billion. You get the point, a ridiculously large number. In reality, the people alive at the IAP would be different numbers of generations separated from this modern person, but that does not change the overall argument.
Each of the four million people alive must occupy a very large number of places in the Han Chinese person’s tree: trillions of trillions of places. But some of those people occupy many more places than others. Although, on average, each of them occupies one 4000000th of his ancestry, some of them might hold a 100000th, some of them more like 100000000th. You would probably find that almost all of the Han Chinese person’s IAP ancestry came from East Asian people, with only small contributions from Europeans, Australians, Khoisans etc.
In summary, a fairly recent Identical Ancestors Point is compatible with much more ancient racial differences.