If you consider the evolution IBM 801 -> ROMP -> POWER -> PowerPC then you might say the that the roots of the PowerPC are from 1975, or 1982, or 1990 or 1991 a

If you consider the evolution IBM 801 -> ROMP -> POWER -> PowerPC then you might say the that the roots of the PowerPC are from 1975, or 1982, or 1990 or 1991 and you would have a valid point in all cases. But it is very reasonable to consider ARM older than PowerPC.