There are no distinct colors. They are only part of a spectrum. The only reason we talk about colors is the arbitrary categorization we do around colors that have significance to us.
For ancient people in general blue had very little significance. There was no reason to create a color category for blue. The clear sky or the clear sea was blue. Apart from that almost nothing.
They still had a number of words to colors that now we would often call blue, like cyanos or glaucos.
Interestingly both the English black and the french white (blanc)originates from the same proto indo-european word meaning to burn or to shine.