This question is tricky to answer because the concept of race as a division into 3 4 or 5 large racial groups is a 18th century notion, something of a follow-on from Linnaean grouping of other species. This was also the time of the development of the African slave trade.

The Egyptian Book of Gates from the 16th century BCE is famous for dividing humanities into four groups: the Egyptians, the Libyans, the Nubians, and the desert dwelling "Asiatic". Lybians were described as the palest.

So people have noticed the differences between different tribes for quite a while, but did not categorize into black and white.